|Spoiler Alert: This page contains spoilers. Read at your own risk.|
The Yotsuba (四葉, よつば, lit. four leaves) Clan is one of the two most influential and strongest houses in the Ten Master Clans. Bearing the number Four (四) in their name, it is a Clan where its members' lives are shrouded in secrecy. The current Head of the Yotsuba Clan is Yotsuba Maya. The next heir of the Yotsuba Clan is Shiba Miyuki and Shiba Tatsuya being her fiancé.
Despite the system of checks and balances to prevent the possibility of Magicians losing control of themselves, placed by the creation of the Ten Master Clans, the Yotsuba Clan is gradually becoming too powerful, even among the powerful Ten Master Clans. With Shiba Miyuki, Shiba Tatsuya, and Yotsuba Maya existing in the same family at the same time, it is believed that the Yotsuba may become an existence that will eclipse the Ten Master Clans. Their ever growing power and influence has caused other Ten Master Clans to be wary of their growth and status to the point that some of the other Family's are trying to weaken them by any means possible.
|“||In terms of numbers, the Yotsuba Clan were plainly outnumbered by the Saegusa and Ichijou Families. Yet, their combat prowess were comparable. In 1 on 1 confrontations, the Yotsuba would have the advantage. Despite their limited numbers, they were more than capable of becoming the counter-terrorism trump card of the government and carry out any action that went beyond the reach of the law that the government needed. In terms of black ops and assassinations, none among the "Numbered Families" could match the Yotsuba Clan.||”|
The Yotsuba and the unique magic they possess originated from the Fourth Institute, the laboratory that created them and is now controlled by them. Their ancestors were magicians with strong mind-manipulation abilities that were selected and gathered together by the Fourth Institute in order to be strengthened and have their primary field of their Magic Calculation Area directly modified as part of their research focusing on "endowment and improvement of magical abilities given by the mind's structure for the usage of Mind Manipulation Magic." 
The "Yotsuba" that were produced at that time inevitably descended from two types of magician lineages. The first lineage was one where a person was born with a Mind Manipulation Magic that was strengthened. The other lineage was one where a person was born with a Magic Calculation Area that is warped by a strong power. These two heritages stand side by side and mix to form the Yotsuba known today. Even those who share the same blood display the two traits randomly. For example, Shiba Miya inherited the traits of the former with Mind Structure Manipulation, a form of Mind Manipulation Magic that only she can use; Maya represents the latter, as she did not acquire any form of Mind Manipulation Magic, but instead a distinctive power from birth.  As for Shiba Miyuki, it seems that she possessed both traits in her power as shown from her abilities of Cocytus, Niflheim, Inferno, and etc.
The Yotsuba Clan is the only family in the Ten Master Clans and 18 Assistant Houses that originated from the Fourth Magic Institute. There are other family's which have the Number 'Four' in their name, such as ‘Yomo’, ‘Shihoudou’, and ‘Watanuki’ but they don't belong to the 28 Houses. 
The Yotsuba are sponsored by a hidden Sponsor who holds considerable influence over the Fourth Research Institute to this day, and whose intentions and requests are regarded highly by Yotsuba Maya and Hayama. 
|“|| "I know what you want to say, Hayama-san. I have no intention of causing discord. I only do this because I believe that obtaining a 'Parasite' is necessary for the Yotsuba."
"Does Madam believe then that studying the Parasite, will bring us closer to the mysteries of Mental Interference?"
"Yes. Just what exactly is the mind, is a question the Yotsuba have been endlessly pursuing. It's said that the Parasites are individual mental information bodies. Information on substance, structure, location......even if only a little, it should give us hints as to the true nature of the mind."
—Conversation between Maya & Hayama
Area of Influence
The Yotsuba Clan's influence encompasses specifically the Tōkai region and both the Gifu and Nagano prefectures. During the Master Clans Conference held every four years, the Head of the Yotsuba Clan gives a report on the status of the regions it monitors. 
The Yotsuba's influence throughout Japan is powerful and vast enough to allow the Clan to systematically alter every personal database at the civilian level, a feat that requires exceptional clearance at the highest level, which showcases how their influence is deep enough to intervene even at the highest level of government. 
It was noted that the Yotsuba only use their power from personal connections, only for self defense and retribution. It seems that they have no lust for power. 
The Yotsuba Clan keeps itself shrouded in secrecy and out of the public's eye unlike the Saegusa Family. 
It is greatly implied that due to the extreme secrecy surrounding the Yotsuba Clan, the general public doesn't know which Magicians are connected to the Yotsuba Clan. It is implied that the only publicly known Magician from the Yotsuba Clan is the current head of the Yotsuba Clan; Yotsuba Maya. As of Volume 17, Shiba Miyuki and Shiba Tatsuya had been publicly announced as members of the Yotsuba Clan.
It is strongly implied that most Magicians related to the Yotsuba Clan don't use "Yotsuba" as their family name but instead use other family names in order to disguise their identities. Also, it is implied that when a person becomes the Head of the Yotsuba Clan, their family name would be formally changed to "Yotsuba".
From a policy of independence if portrayed positively, or the policy of being self-centered, if portrayed negatively that the Yotsuba adopted, they have always adopted the stance of not caring about what other Houses do. It has been stated by Katsuto that because of the high level of secrecy surrounding the Yotsuba, nobody knows what they've done or plan to do. 
The mountain village where the Yotsuba reside, is in a narrow valley not recorded on any map, which is in the old Yamanashi Prefecture that bordered the old Nagano Prefecture.  Due in part to the village not being recorded on any map, it has no designated address for receiving delivery's. The Kobuchizawa Station is the nearest station to the village, for a vehicle to come and pick up visitors. 
There is a tunnel that leads to the entrance of the village. Inside the tunnel are branches of a pathway with a mechanism that needs a flow of Psion waves in a certain waveform at specific points in order to be able to stay on the route which leads to the Yotsuba's Village. The tunnel provided an automatic gate of Non-Systematic Magic. The mechanism essentially cuts off the village from the outside world, by land transportation. 
A barrier surrounds the village to repel intruders, and it can easily be decomposed by Tatsuya's Decomposition. The catch is, if until the barrier is rebuilt by Magicians with recognition inhibitors, they'd be overworked day and night because doing so isn't a simple task. 
In the center of the village lies a conspicuously large single-story Manor, the Yotsuba Main House. 
In Tokyo, the Yotsuba have a safe and secure residence for Tatsuya and Miyuki to use that was prepared for them. 
Near the Main House, there is a complex which is the residence of the Kuroba Twins' grandmother, Yotsuba Yume, younger sister of Yotsuba Genzou, Tatsuya and Miyuki’s deceased grandfather, as well as aunt to the current Clan Head, Yotsuba Maya. 
The Main House conceals the address of the Old Fourth Research Institute. Due to the high confidentiality of the Old Fourth Research Institute, only the name is known, and the address is not known even to the highest government and military officials. As the Yotsuba Clan had inherited the facility, they went around literally erasing the memory of anyone who knew this secret, completely hiding the location. 
The Main House is a rather large building done in the style of a traditional Samurai residence. A description of an outsider's impression of the Yotsuba Main House as seen from outside of the gate. Compared to a typical residence it is certainly spacious. Even calling it a mansion does not feel like a misnomer. However, someone who looked at the grand mansions of those like the Saegusa Family and Ichijou Family would probably be rather surprised by its simple snug appearance. The Yotsuba do not care about the spaciousness of their house. Because the Yotsuba Clan, who maintain a systematic policy of secrecy, would never invite a large number of outsiders as guests. Perhaps they think a grand mansion would only be an encumbrance. 
In contrast to the Eastern style of architecture for the exterior of the house, the big reception room is done in the Western style. There are even paintings of landscapes adorning the brightly hued walls, not reproductions either; but rather, these were original oil paintings. And the stately natural wood table in the middle of the room could easily seat over ten people. 
The Audience Chamber gives off the impression of emptiness. This was possibly due to the fact that, instead of the space being occupied by the legs of over ten chairs, there are only the four legs of a sofa placed by a table; also, aside from the table and sofa, there are almost no furnishings, which appear to leave all too much space leftover in the room. Making the room feel unnecessarily vast was probably for the purpose of psychologically inducing a feeling of oppression. 
Based on the fact that they possess unique abilities unmatched by other families and have a select few but extremely powerful group of Magicians, the Yotsuba Clan is a special entity within the Ten Master Clans. 
Unlike other families that possess similar magic that is inherited through blood relations, the Yotsuba Clan doesn't have Magicians that possess similar abilities, but instead unique ones. 
While possessing an aptitude for having Mental Interference Magic is an important quality for the Yotsuba Clan Head to have, it isn't an absolute condition. Up to the previous Clan Head, Yotsuba Eisaku, he was highly versatile in Mental Interference Magic, but Miya who had the powerful ‘Mental Design Interference’ Magic hadn't been selected to be the next Clan Head, instead Maya was chosen. 
The 28 Houses were originally conceived to be Side Branches that stem from the development of Magicians, however, the Yotsuba Clan are the only ones to have adopted a Side Branch System. 
- Yotsuba (Head Family)
|“|| In regards to the secret feud between the Yotsuba and Dahan; on the Yotsuba side, there were thirty dead. From this war, the Yotsuba lost the head of the Clan and half of its fighting strength. On the other side, Dahan's dead were approximately four thousand. For the sacrifice of a mere thirty people, the Yotsuba Clan assassinated four thousand: cabinet ministers, high class bureaucrats, officers, magicians and researchers; as for the continent of Asia, it had all its research results on modern magic annihilated.
Due to this damage, Dahan suffered an internal collapse after one year and the Great Asian Alliance unified the continent of Asia. As for East Asia, the antagonism between the North and the South came to a resolution; as for the northern hemisphere, a resolution for the world wide border conflicts was jury-rigged. It was the end of World War III. And among those who knew the truth about the collapse of Dahan, the Yotsuba were feared as "Untouchable".
The Yotsuba Clan currently possesses one of the strongest Magicians in the modern era. Yotsuba Maya is known throughout the world as the "Demon Lord of the Far East", the "Midnight Queen", and is the current Head of the Yotsuba Clan. 
Elders 長老 (素体)
- Shiba Kuuya (司馬 空故) - (Deceased)
- Shinonome Maaya (東雲 真彩) - (Deceased)
Great Grandfathers Generation 曾祖父世代 (第四研設立接改姓)
- Yotsuba Kazuma (四葉 和真) - (Deceased)
- Higashiyama Motohide (東山 元英) - (Deceased)
- Yotsuba Ayame (四葉 彩夢) - (Deceased)
- Yotsuba Hyouma (四葉 兵馬) - (Deceased)
- Yotsuba Yuuma (四葉 勇魔) - (Deceased)
Grandfathers Generation 祖父世代 (四葉家確立)
- Yotsuba Genzou (四葉 元造) - (First Clan Head, Deceased)
- Abe Yasuyo (阿部 泰夜) - (Deceased)
- Yotsuba Eisaku (四葉 英作) - (Second Clan Head, Deceased)
- Kuroba Juuzou (黒羽 重蔵) - (Former Branch House Head, Deceased)
- Yotsuba Yume (四葉 夢女)
- Yotsuba Motosuke (四葉 元輔) - (Deceased)
- Yuuki Fuyuhiko (結城 冬彦) - (Deceased)
- Tsukuba Ayaka (津久葉 彩歌) - (Former Branch House Head)
Parents Generation 父母世代
- Mashiba Shinsuke (真柴 真佐) - (Branch House Head)
- Shiba Tatsurou (司波 龍郎 [旧姓・司馬])
- Shiba Miya (四葉 深夜) - (1st Wife, Deceased)
- Shiba Sayuri (司波 小百合) - (2nd Wife)
- Yotsuba Maya (四葉 真夜) - (Third Clan Head)
- Shiiba Hidetsugu (椎葉 英嗣) - (Branch House Head)
- Shizuka Haruto (静 陽人) - (Branch House Head)
- Shibata Osamu (新発田 理) - (Branch House Head)
- Mugura Asumi (武倉 藍霞) - (Branch House Head)
- Tsukuba Touka (津久葉 冬歌) - (Branch House Head)
- Andou Seiji (安東 青司)
Candidate Generation 候補世代 (次代当主)
- Shiba Tatsuya (司波 達也) - (Fiancé of the Next Clan Head)
- Shiba Miyuki (司波 深雪) - (Next Clan Head)
- Kuroba Ayako (黒羽 亜夜子)
- Kuroba Fumiya (黒羽 文弥)
- Shibata Katsushige (新発田 勝成)
- Tsukuba Yuuka (津久葉 夕歌)
In response to Maya's tragedy, the Yotsuba enacted a policy of attaching guards to Clan Members who possess an especially superior disposition for magic, which is when the Guardians were created. 
The Guardians of the Yotsuba Clan bear the duty of preserving their primary's life even at the cost of their own. This title comes from the combat slaves that once rescued a young woman from the Yotsuba Clan from enemy attack and were responsible for preserving the Yotsuba bloodline. On the surface, this duty differs little from ordinary bodyguards, but temporarily hired bodyguards are fundamentally different from Guardians. While Yotsuba Guardians aren't selected from birth, once selected, their term is for life. Though they were the same as bodyguards in that they serve for 24 hours a day, 7 days a week, Guardians don't possess the right to resign from their duties. Since Guardians are only relieved when their primary is released from protection, to this day, without exception, Yotsuba Guardians are done with their duty only until the day they die. 
Guardians receive no monetary rewards. All the living necessities are provided by the Yotsuba. Whenever cash is needed, the Yotsuba supply it. To be correct that is not a reward, it is the cost of maintaining the power of protection. Guardians have no private life of their own. All of them, the male Guardians and the female Guardians, whether they call the one they protect Master or Mistress, are devoted to serving that person. Guardians do not normally use the designations of "Master" or "Mistress" when present within the Clan. 
- Shiba Tatsuya (司波 達也) [Mistress: Shiba Miyuki]
- Only Miyuki can release Tatsuya from his duties as a Guardian, though another Guardian, likely of the same age and gender, would be dispatched to her. Of course, Miyuki hopes to retain Tatsuya as her Guardian for reasons that go beyond her own stubbornness. Within the Yotsuba Clan, a Guardian's duty is of the highest priority. While serving as Miyuki's Guardian, he wouldn't be assigned any meaningless tasks. Nor would he receive any dirty jobs. 
- The Yotsuba Clan hasn't relinquished their hold on Tatsuya. He remains a Yotsuba Guardian. Only under the conditions of his role as a Guardian not being compromised, is he allowed to participate in military missions. Besides guardian responsibilities, the Yotsuba Clan is not allowed to assert their precedence. That is the agreement the National Defense Force 101 Independent Magic-Equipped Battalion has with the Yotsuba Clan. 
Sakura Series (桜・シリーズ)
The Second Generation of the modified “Sakura” Series are born of parents that were genetically engineered to grant them powerful magical abilities. The “Sakura” Series’ specialty is creating heat resistant barriers that repel physical objects. Though its functionality and variability are not on par with the Juumonji Family’s “Phalanx”, judged solely on its utility as a defensive mechanism. 
- Sakurai Honami (桜井 穂波) - (Deceased) [Mistress: Shiba Miya]
- Sakurai Minami (桜井 水波) [Candidate; Mistress: Shiba Miyuki]
Bard Series (楽師・シリーズ)
The Modified Body ‘Bard Series’ is a group of Magicians who are especially good at Systematic-type Oscillation (Vibration) Magic, especially in interfering with sound waves, and they are Magicians made for combat. However, the tendency of their specialized magic for fighting is different, specifically when it comes to search operations, detecting interference, bewitching and damage mitigation type magic’s rather than combat magic. 
- Tsutsumi Kotona (堤 琴鳴) [Master: Shibata Katsushige]
- Tsutsumi Kanata (堤 奏太) [Master: Shibata Katsushige]
There are eight butlers that serve the Yotsuba Clan under specific designations, however, Hayama is in-charge of the lower seven.
- Hayama Tadanori (葉山 忠教) - (Head Butler)
- Hanabishi (花菱) - (2nd Butler/Resource Manager)
- Kurebayashi (紅林) - (3rd Butler/Fourth Institute Manager)
- Aoki (青木) - (4th Butler/Financial Manager)
- Kuroda (黒田) - (5th Butler/Scout Recruiter, Real-estate Manager)
- Mr. Shirakawa (白川) - (6th Butler/Assistant Butler to Hayama)
- Kimura (木村) - (7th Butler/Mayor, Village Real-estate Manager)
- Obara (小原) - (8th Butler/Transportation, Police Riot Manager)
There is known to be at least one lesser butler that works at the Yotsuba Main House. 
There are several maids, though Shirakawa is in-charge of all of them.
- Mrs. Shirakawa (白川) - (Head Maid)
In Japan there are companies that use "Yotsuba" or "Yatsuha" in their name. The Yatsuha name is associated with the Four Great Systems and Eight Major Types in Modern Magic as well as the Garbhako'sa-Dhatu Mandala, so modern corporations enjoy using the name. Using the name of the Yotsuba Clan from the Ten Master Clans is considered a taboo by individuals affiliated with magic. If Japanese corporations use the Yotsuba name, both intelligence and criminal organizations fear to rouse the Yotsuba Clan's wrath by harming their assets. There are companies that pretend to be affiliated to the Yotsuba Clan, even if they don't say otherwise. 
Four Leaves Technology
- Main Article: Four Leaves Technology
FLT, the literal translation is "Four Leaves Technology", although the official company records and brand name intentionally uses only "Four Leaves". It is secretly funded by the Yotsuba Clan and they hold the power of attorney over the stocks that Tatsurou received when Miya died. 
The Yotsuba Clan has hotels in every region throughout Japan that are either under their direct patronage or receive funding from them. The Kuroba Family in particular when due to the nature of their work, they end up going on numerous business trips and use these hotels. 
Secret Techniques/Unique Magic
- The Yotsuba secret technique to cast at fast speeds without the use of a CAD. It is made possible by mentally "carving" the images of the Activation Sequence into memory, allowing the user to recall the Activation Sequence directly from memory instead of a CAD to construct the Magic Sequence of the spell in the Magic Calculation Area of the brain. It can only be used with single systematic spells that are not overly long or complex.
➨ Psion Transfer
- The ability to transform information into Psion signals and transfer that information through the nervous system and into another person's subconscious Magic Calculation Area through physical contact is unique to the Yotsuba Clan. Ordinary Magicians need to plug in the target data into their Magic Calculation Area when they invoke magic, however, the data is a Magician's perception in digitized form and generally can't be shared. 
- The name of the Shiba branch family might be a reference to the now extinct Shiba Clan.
- Both the "Old Yamanashi and Nagano Prefectures", are so called due to the fact that both prefectures have had towns and villages merge into and out of other prefectures as well.
- ↑ Volume 16, Chapter 7
- ↑ 2.0 2.1 2.2 Volume 8, Untouchable - The Nightmare of 2062
- ↑ 3.0 3.1 Volume 13, The Ten Magician R&D Institutes
- ↑ Volume 8, Chapter 10
- ↑ Volume 11, Chapter 16
- ↑ Volume 17, Chapter 5
- ↑ 7.0 7.1 7.2 Volume 4, Chapter 12
- ↑ Volume 13, Chapter 6
- ↑ 9.0 9.1 Volume 3, Chapter 6
- ↑ Volume 9, Chapter 4
- ↑ Volume 12, Prologue
- ↑ Volume 16, Chapter 3
- ↑ 13.0 13.1 13.2 Volume 16, Chapter 5
- ↑ Volume 16, Chapter 4
- ↑ Volume 15, Chapter 6
- ↑ Volume 17, Chapter 1
- ↑ Volume 8, Chapter 3
- ↑ Volume 8, Chapter 1
- ↑ 19.0 19.1 Volume 8, Chapter 5
- ↑ Volume 16, Chapter 2
- ↑ Volume 11, Chapter 15
- ↑ Volume 3, Chapter 4
- ↑ 23.0 23.1 Volume 6, Chapter 2
- ↑ Volume 8, Chapter 2
- ↑ Volume 12, Chapter 0
- ↑ Volume 8, Chapter 12
- ↑ 27.0 27.1 Volume 6, Chapter 3
- ↑ Volume 3, Chapter 2
- ↑ Volume 14, Chapter 4
- ↑ Volume 15, Chapter 1
- ↑ Volume 6, Chapter 7
This category has the following 3 subcategories, out of 3 total.
Pages in category "Yotsuba"
The following 45 pages are in this category, out of 45 total.