Morinomiya Youichi is the late son of Morinomiya Youko, chairwoman of Morinomiya Academy. He worked as a teacher at the school, and tried to get the students to join the Babysitter Club he established with his wife.
Unlike his mother, Youichi's warmth and kindness was on the surface. He often tried to encourage those around him to enjoy life if he felt they were listless or overly serious.
In order to accommodate the members of the school staff who had nobody to look after their young children, the daycare facility was established. However, there was no room in the budget to hire staff members to care for the children. In an attempt to resolve this issue, Youichi and his wife established the Babysitter Club and tried to get students to join. Unfortunately, the club did not garner any interest among the student body.
Youichi later heard that his former student Usaida Yoshihito had been drifting aimlessly following his graduation. Thus he approached Usaida one night in the hopes that his old student might find his purpose while helping with the daycare's predicament. Usaida agreed to help for Youichi's sake, and prepared to take the required service course in order to qualify for the childcare position.
Before those exams took place, Youichi invited Usaida over to the daycare both in order to introduce him to the environment and another, more personal request. The school secretary, Sawatari Yukari, was pregnant. Since her husband was working in Turkey, Youichi wished for Usaida to accompany her to her parenting classes.
Youichi later took a congratulatory photo with Usaida commemorating the latter passing the exam.
He and his wife were both victims of the same plane crash that took the lives of Ryuuichi and Kotarou's parents. He did not have any children of his own before dying, leaving his mother with no living relatives.