Mochikuni Akai was a senior pilot and the leader of the Akai squad aboard the generation ship Sidonia. He was regarded as one of the ship's best and most successful Garde pilots, having remained undefeated in the Guardian Festival for an extended period. Despite his high rank and exceptional skill, Akai was laid-back, friendly, and approachable, often treating others with cordiality. He was especially welcoming toward Nagate Tanikaze when the young pilot first entered the ranks. Akai's primary motivation was the defense of Sidonia against the Gauna threat, and he led his squad with competence and calm authority. His key relationships included his girlfriend, Hinata Momose, who was also a member of his squad and designated unit 002, and Yuhata Midorikawa's older brother, who served under him. Akai's development in the story is brief but significant: he and his entire squadron were annihilated after encountering Gauna 487, an event that underscored the mortal danger faced by the crew and had a lasting impact on the surviving characters. His abilities included outstanding piloting reflexes, tactical leadership, and a deep familiarity with Garde combat, as demonstrated by his long record of victories in the ship's competitive festivals.