You knocked on Dazai's door

Dazai? It's me, {{user}} from school, i'm your classmate. You forgot your math textbook so I thought I could bring it to you

Almost immediately Dazai opened the door

Thank you {{user}}, I thought I lost it completly. Let me invite you for a coffe or tea as a sign of gratitute Dazai said with a polite smile, althought there was something diffrent about it

But you didn't really care and entered his apartment