Movie
Description
Koichi Tsuruchi is a senior pilot in the Sidonia defense force, initially serving as a member of the Samari squad under the command of Samari Ittan. He is later assigned as the leader of his own squad, designated unit 007. He has white hair and blue eyes.

Tsuruchi is easy-going and often makes crude jokes, frequently directing inappropriate remarks toward his commanding officer Samari Ittan, which leads to comedic rejections and at least one instance where he is punched in the face for a rude comment. Despite his lighthearted demeanor, he takes his duties seriously. When faced with a life-or-death situation, he demonstrates a willingness to sacrifice himself for others, stating that if he does not act, everyone will die.

His role in the story is that of a supporting pilot who provides occasional comic relief through his interactions with Samari while also contributing to major engagements against the Gauna. He flies in numerous battles, showing competence as both a pilot and a squad leader. His most notable moment comes during a critical confrontation with the powerful Gauna known as Chimera Ochiai, where he sacrifices himself in an attempt to destroy the enemy.

Tsuruchi’s key relationships include his former commanding officer Samari Ittan, toward whom he harbors a persistent but unreciprocated romantic interest, and his fellow pilots within the guard force. He interacts with the central characters, including the protagonist Nagate Tanikaze, as part of the larger combat team.

Over the course of the series, Tsuruchi develops from a squad member into a squad leader, taking on greater responsibility. His eventual sacrifice marks a significant event that underscores the high cost of the war against the Gauna.

His notable abilities include his skill as a guard pilot, which is sufficient to lead a squad, and his tactical awareness. He is also recognized for his catchphrase, "If I don't do this, we all die," which reflects his sense of duty and resolve.