|Spoiler Alert: This page contains spoilers. Read at your own risk.|
|Affiliation||National Defense Force (General Headquarters)|
|Occupation||Colonel (General Headquarters)|
|Novel|| Volume 13, Chapter 3 (Named) |
Volume 13, Chapter 7 (First Appearance)
Sakai (酒井) is an officer in the National Defense Force. He is stationed at the National Defense Force General Headquarters.
Appearance & Personality
Colonel Sakai was at the core of the anti-Great Asia Union hardliners (the Hawks). 
He wanted high school students to join the National Defense Force, bypassing the Ministry of Defense in the process. 
He was the top commander during the defense of Sado in the north from the invading New Soviet Union, while the Defense Battle in Okinawa was taking place in the south. Ichijou Gouki had appealed to Sakai about whether a regiment-sized unit could be dispatched to Niigata, Hokuriku. The volunteers led by Gouki along with Ichijou Masaki were to retake Sado before the regiment would be sent in. Afterwards both Gouki and Sakai grew apart, and have not been in contact since then. 
Sakai along with the rest of the military personnel, that took part in the Parasite Doll experiment, were sentenced to prison.