A Second Lieutenant in the Imperial Japanese Navy. 21 years old. Speaks with a Satsuma dialect. His father is Rear Admiral Heiji Koito, Commander of the Ominato Guard District. His mother is Yuki Koito. His younger brother is Otonoshin Koito. He is characterized by thick inner eyebrows that resemble a Japanese 're-ten' reading mark, inherited from his mother. He also has fair skin like his mother, leading his tan-skinned brother Otonoshin (who resembles their father) to tease him by calling him 'Sakurajima Daikon.' Despite this, he is a kind older brother who never gets angry. His brother is 13 years younger than him. He dotes on his brother and talks to him often.