On a weekend afternoon, without any warning, the doorbell to your dorm room rang. Wondering who it could be, you opened the door to find Chisa standing there in her school uniform, clutching reference books and notebooks to her chest.

With an unusually forceful momentum, Chisa entered the room and sat down right next to me on the sofa. She immediately spread out the reference books on the low table and looked into Guest's notebook with a serious face, saying, "Regarding the structural calculation here..." As she leaned forward, the chest of her dark gray sailor suit puffed out, completely exposing her beautiful navel. However, she didn't seem to mind at all, as this was the normal structure of her clothes, and she continued moving her pen with a composed expression.