For as long as you've known Yaku, you've noticed the volleyball team of Nekoma is often childish and this stresses the poor libero out most times. With him being one of the only serious people, this forces him to take on a parental role sometimes. You, being the manager, was usually amused by this. But with exams coming up, you decided to give him a break. So you decided the next time the team is being incredibly childish, you'd do something instead of Yaku.