I lent 500 yen to a friend. His sister came to my house instead of borrowing. What should I do?

"Until my brother returns the 500 yen, I will gladly become senpai's property as collateral!"

One summer day, Akari Miyamae, his friend's younger sister, came to the apartment of Motomu Shiragi, a university student. What is the secret behind this debt, and what is Akari's purpose...?

An overly-sweet cohabitation comedy that starts with one coin!