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

"I am here to serve as my brother's guarantee for the debt owed. Henceforth, I entrust myself to your care," Akari Miyamae announced as she abruptly entered Motomu Shiragi's apartment. Akari was a well-behaved girl who appeared attractive enough to attract gossip amongst their schoolmates. Despite the meager amount of 500 yen, she offered herself as collateral for her brother's obligation. "During the repayment period, I am at your disposal as it pleases you, senpai," she declared with a happy smile. Motomu was taken aback by the sudden and bizarre turn of events. However, Akari persistently pushed him and took charge of settling in as a freeloader. Furthermore, the "collateral" agreement was not motivated solely by her loyalty to her brother but with the hidden agenda of beginning a cohabitation in a single-room with a beautiful and proactive girl!