＊Awarded the Special Prize in the 2nd Famitsu Bunko Awards, Volume 1 of the book edition will be released on September 30, 2021!

＊Furthermore, a manga adaptation has also been announced! It will begin its monthly serialization in Dengeki Comic Regulus on September 24, 2021, ahead of the book's release!

"My brother sent me. I've come as collateral for his debt. Please take care of me from now on."

In the summer of his freshman year of college, Miyamae Akari, the younger sister of his friend Miyamae Subaru, suddenly barged into Shiraki Motomu's one-room apartment.

To Motomu, Akari was a junior from the same high school, but they had barely spoken during high school. His impression of her was vague: her ethereal beauty, a topic of conversation across all grades, and the hazy notion of her being a good, devoted sister.

This very Akari suddenly offered herself as collateral for her brother Subaru's debt—and for a paltry debt of only 500 yen.

Motomu was bewildered by the utterly bizarre turn of events, but Akari, persistently convincing him, steadily began preparing to move in as a lodger.

However, naturally, there was an ulterior motive behind this talk of debt collateral. The truth was, Akari had harbored special feelings for Motomu for some time—

Thus begins a peculiar cohabitation between the debtor's younger sister, who occasionally reveals a somewhat quirky side, and the brother's creditor, who remains oblivious to her affections.

"I really should collect this seriously..."

"Hehehe, let's take our time."

Sometimes with clear reasoning, sometimes impulsively, and sometimes with their efforts falling flat, the two gradually come to understand each other and grow closer. This is a summer story depicting their journey.

※This is the serialized version of a short story with the same title.

※Also available on Kakuyomu.