Greatest common Divisor

Our delivery service's regular customer, Aizawa-san in room 411, is always wearing a rabbit head! Why is he wearing something like that in the first place? Pervert? Everyday he sends or receives delivery but you can't see his face, and he's almost mute, there's nothing scarier than this. But one day, still wearing the rabbit head, he grabbed tightly onto my arm, "thank you, I'll see you again tomorrow!" Saying it in such an embarrassed way- My heart beats so fast. **Included one-shots:** Ano Egao wo Mou Ichido, Bokura no Saidai Kouyakusuu.