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Yoshida Mikihiko (吉田 幹比古) is a Course 1 student (and formerly a Course 2 student during his first year at First High School, transferred due to the reshuffling of students caused by the introduction of the Magic Engineering Course) in First High School. Mikihiko is the Public Morals Committee chief (succeeding Chiyoda Kanon) and Erika's childhood friend.
Appearance and Personality
Mikihiko was initially described as a slender, nervous-looking boy during his short appearance in the first volume on the enrollment day when he left the classroom first, skipping guidance and proceeding straight to registration unlike his other classmates.
In a scene in the first chapter of Volume 3 that serves as his formal introduction into the series, despite being slender, he was depicted as someone who can be more accurately called well-built.
Mikihiko is extreme in his aloofness and not once was he seen conversing with anyone in their class, making him look anti-social. It was revealed later that he was simply a shy person. He also takes an interest in Shibata Mizuki's unique 'eyes', which later develops into romantic feelings for Mizuki herself, as it is hinted in the novels.
He is an earnest person, sometimes prone to anxiety, much of it stemming from his belief that he should have been able to, but could not, wield magic in the same way as in his past. By his own admission, despite making him bitter and lack confidence in himself, the accident that happened to him and subsequent struggles have made him more humble and open-minded (to the point that he studies modern magic as much as possible to try to make up for his deficit). At times, he pushes himself too much and is very hard on himself, having unrealistic expectations because of his pride.
Despite being somewhat closed off to others initially, he begins to open up and trust others, to the point that he even reveals secrets of his own magic to his closest friends.
Later, he begins to regain his confidence as he regains his power, but loses none of the earnestness and perspective he gained from his struggles.
Mikihiko is a direct descendant of the Yoshida Family — a family which is neither a part of the Ten Master Clans nor the Hundred Families — but is prestigious due to their traditional methods and supreme knowledge in Ancient Magic.
Yoshida Sachihiko is the current head of the Yoshida Clan. He himself was only the second son of four, although the reason he became Clan Head is because he can perform "Hoshi Oroshi no Gi", and that any such member whom is best at performing the ritual becomes the next head regardless of lineage. 
Mikihiko himself has an older brother, Yoshida Motohiko, who is 7 years older. Mikihiko has 9 other male cousins.  A few years prior to when the series started, Mikihiko was held to be a prodigy among their family. However, due to an accident, he fell from grace and was not able to use his power the same way for a long time, especially in regards to his casting speed. He became desperate for a solution and began to look to Modern Magic and CADs to try to compensate for his shortcomings (CADs are known to improve the casting speed of spells) without much success.
This was defined to be a mental problem, as he was able to use his magic perfectly well in the Nine Schools Competition, albeit with more efficient magic spells that Tatsuya designed instead of the unnecessarily convoluted spells from Ancient Magic that his family practiced.
Gradually, after the Nine Schools Competition, he has slowly recovered most, if not all of his power, leading to a drastic increase in the technical portion of his grade and his subsequent transfer into Course 1 for his second year.
In the beginning of his second year he is picked as a member for the Public Morals Committee as replacement for Tatsuya who became a Student Council member. In October that year Mikihiko becomes the Public Morals Committee Chief, succeeding Chiyoda Kanon.
Mikihiko uses a mobile-terminal-shaped CAD, along with the Ancient Magic tools for casting assistance.
He started using a CAD (also said as a supplemental CAD) that he had himself prepared based on Tatsuya’s suggestions and his own ideas. It is designed to streamline Ancient Magic that utilizes both incantations and talismans. It has a fan-like body made of metal strips that have engraving of various incantations and formations – connected to another device inside his sleeve that has activation sequences. The metal strips are favored by practitioners, as iron strips form a conduit for Psions. It replaces any need for incantation. 
Divine Earth Magic
- Main Article: Divine Earth Magic
The Divine Earth Magic of the Yoshida Family is an Ancient Magic that belongs to the Shinto System and more
specifically the branch concerned with Earth Deities within the Shinto System (deification of the country).
- Magical Mist and Barrier - This magic sets up a barrier around an area and fills it with mist. The caster has complete oversight of the space and can freely control the density of the mist. Mikihiko used it in the Monolith Code match against Ninth High School.
- Earthshaker (地鳴り) - It is an Oscillation-Type Magic that creates illusions which, when applied to ground, gives the impression that the earth is shaking. 
- Earth Splitter (地割れ) - It is a magic that causes illusions that the earth is cracking. The ground does not physically tear apart, but separates by the force exerted within. 
- Wild Hair (乱れ髪) - This technique is done by commanding the air currents that brushed over the earth's surface to create the image that something was wrapped around the target. It gives the illusion of being entangled. 
➨ Ant Hell
- Ant Hell (蟻地獄) - This magic spell creates an illusion when the target feels like he is being pulled into the earth. 
- 'Wataboshi' from Ancient Magic. Wataboshi is based on the application of Ancient Magic concept “Riding the Wind”. It combines gravity nullification and inertia cancellation into phenomena alteration. 
- Thunder Spawn - Thunder Spawn recreates a small scale thunderbolt in a small space. It releases electricity towards the target. As a Dispersion-type magic, it extracts electrons from within an object and then channels the electricity produced. This magic creates a small thunderbolt in a small scale.
- It is described as only an inferior imitation of the true magic that actually manipulates the clouds, 'Thunder Cloud', but the discharge and voltage created being just as powerful.
- Mikihiko used this magic the to apprehend the intruders with Tatsuya's help at Fuji Base at night during the Nine Schools Competition. Thunder Spawn is very similar to the Modern Magic "Thunder Child" and is an inferior version of the magic, "Thunder Clouds" that actually manipulates clouds. However, the discharge and voltage is equally powerful.
- Thunder Child (雷童子) - This magic as been described as a variant of Thunder Spawn. Mikihiko used this magic during the Monolith Code final against Kichijouji Shinkurou.
- Thunder Child is very similar to the Modern Magic "Thunder Spawn" which is an inferior version of the magic, "Thunder Clouds" that actually manipulates clouds.
- Comparing Thunder Child & Thunder Spawn
- The Dispersion-Type Magic, Thunder Child when compared to Ancient Magic, Thunder Spawn is more powerful as it is able to channel higher amounts of electricity but has less control. The Thunder Child, from the 4 Systems & 8 Types, is a fundamental technique that extracts electron from within an object, replacing the electron's phenomena. 
It is a type of Ancient Magic which uses independent Information Bodies commonly called 'spirits' to interact with other Information Bodies.
- Summoning Magic - One of the core techniques within the various magics of the Yoshida Family lay in this magic.
- Sense Tuning - An advanced technique that allows a user to match his/her senses with a spirit. Normally, Magicians are hindered by distance, not because it's harder to cast magic, but because Magicians have greater difficulty perceiving the distance. With Sense Tuning, a magician can feel the proximity of a spirit even if it were far away, circumventing the range issue. Mikihiko can only tune two of his five senses at a time. For the Monolith Code, he used Visual Tuning where he matches his view with the spirit.
- Echo Maze - Is a magic that barrages targets with high and low frequency sound waves, confusing them. The high frequencies are used to distract the opponents, while the low frequencies wreak havoc on their inner ears, destroying their sense of direction. With their senses scrambled, targets are unable to retaliate if they do not realize their true predicament. In areas where surroundings look the same, like a forest, targets are unable to realize the problem and are thus incapable of defending with magic, which is the only way to defend.
- In Mikihiko's case, he casts his magic with the aid of spirits, so even if targets manage to find the source of the sound waves, all they find are spirits, making it an excellent stealth weapon.
- Earth Pit (土遁陥穽) - Earth Pit is an Ancient Magic that Mikihiko used during a ten-against-one mock battle with Katsuto in Volume 6 of the light novel. It is a spell that plummets the enemy into an earthen tunnel, disrupting the senses and hampering movement for the caster to buy time and escape. Against an inferior opponent, this technique is sufficient to completely restrict their movement and capture them.
- Karura-En (迦楼羅炎) - Is a Anti-Demon magic, specifically designed to counter things that were not information bodies. The independent information body that formed its "flames" shot towards the coordinates that is designed. It is a magic launched against the detached information body that brings harm to the Parasite. It is used against the Parasites.
- Exorcism Cut (切り祓い) - Is a Anti-Demon magic, though its strength paled in comparison to ritual magic, the magic’s speed rivaled that of the arts used by Magicians of the Forbidden Sect. Forms a blade made of Psions that shreds the threads of a Parasite in its information body form.