Re: Zero kara Hajimeru Isekai Seikatsu - Episode 29 - Subaru Points to Sky

Subaru's trial involved confronting his past and changing his behavior in it.

Subaru became a shut-in because his self-identity took a hit when he wasn't as smart or athletic as he thought, which would have just needed him to study or practice harder. When he realized he was living in the shadow of his popular dad and just needed to be himself, he felt like he could go back to school.