In the second season of ReZero, we had a special episode where he faces the first trial of Echidna, having to challenge his past.
We learned there that because of a situation in his childhood he stopped going to school and became a hikikomori, that wasn’t all of a sudden either, he started going to school less and less until he stopped altogether.
Hikikomori is the name we give to people who are locked in their rooms, don’t go out, don’t go to school, don’t work, live in isolation.
In a Q&A that the author of ReZero gave, he revealed what Subaru’s day was like in his Hikikomori days, before he was transported to the other world and met Emilia.
Subaru Hikikomori’s daily life:
Go to sleep
Wake up, spend 4 hours on your hobbies
2 hour nap
wake up and have dinner
Hobbies that consist of staying on the internet, reading manga and weight training
Hobbies until bedtime.
As you can see, a totally healthy routine both physically and mentally, and he walked right out of that into a world full of suffering and death that seems to never end.