友人に500円貸したら借金のカタに妹をよこしてきたのだけれど、俺は一体どうすればいいんだろう

Akari Miyamae suddenly barged into Motomu Shiraki's apartment. She was a good girl who loved her brother and rumors of her beauty extended even beyond her school. "I'll gladly become my senpai's property until my brother pays back his debt of 500 yen!" she declared happily. Motomu is bewildered by this outlandish turn of events, but Akari forcefully convinced him as she prepared to take up residence. Naturally, there's more to the story. The exciting life of living with a beautiful girl in a one-room apartment begins! (Source: Kadokawa, translated)