Mishima Taiga

You's biological father. He met You's mother, Kogasaka Kasumi, when she was in middle school and fell in love at first sight. He then became a teacher at Kasumi's high school to get closer to her but was devastated to find out that she had a boyfriend already.

Later on when Kasumi's memories of her boyfriend were wiped by Ren, she became close to Taiga and had their son You. Kasumi would soon after regain her memories and leave Taiga. He is also the old director of Hibarigasaki's planetarium, and the one who gave Isuzu her telescope.