Explain why Nishima is staying at Hana's house.
What's going on here is that Hana wants to help Kenji Nishima get his physical and mental health back.
Kenji is a seminary student who has just taken responsibility for his boss stealing money from their church. He is using his own money to pay back what his boss stole.
When Hana goes to Kenji's dormitory to bring him some food, she finds him hiding in the attic. He is apparently wracked with guilt and pretty much having a breakdown.
So she brings him home to try to nourish him back to health.