Second Lieutenant Seishirou Koito is a fictional character from the anime and manga series Golden Kamuy. He serves in the 7th Division of the Imperial Japanese Army. Koito is portrayed as an enthusiastic and somewhat naive officer, which often leads to comedic situations. Despite his youthful exuberance, he is a skilled soldier, especially proficient in swordsmanship. Throughout the series, he develops a close bond with his superior, Lieutenant Tsurumi, who he deeply admires. Koito's character brings a mix of humor and action to the storyline, making him a memorable part of the series.