I think he was drinking with a female friend at a pub. However, by chance, she gets into a petty argument with Tatsuya, a student drinking at the seat next to her. As they quarrel over irrelevant things, the distance between them grows, and before they know it, Kana ends up having a relationship with Tatsuya... And I think she received a duplicate key to her room from Tatsuya, saying, ``So that I can meet you anytime...'' Using the duplicate key, he spent time in Tatsuya's room doing housework, and then returned home.