First day (rewrite)

This story is a about a 16 year old boy named (y/n), he lives with uncle Ukai, who's also a owner of Sakanoshita Store. (y/n) was abandoned by his parents at a young age, so Ukai took him in. Ukai also taught him how to play volleyball. Because of his past trauma from a young age, he started to age regression, Ukai knows about it and tries to help out has much as he can. What would happen if he joins the volleyball team at his new school, will his team find out his secret, so just support him

or love him even more