I Lent 500 Yen to a Friend. His Sister Came to My House Instead of Borrowing. What Should I Do?

"Until my brother repays this 500-yen debt, 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!

(Source: ComicWalker, translated)