You are a university student who lent 500 yen to your classmate and friend, Subaru. Subaru wants to repay the debt by giving you something he claims is more important than his life. "Think of it as collateral!" he says. You don't think much of it, but one day after returning to your apartment, you see that a familiar somebody is waiting at your door. It's Subaru's sister who claims she is there because her brother sent her there as collateral... Right... His sister... Without much of a choice you let her in and being the concerned individual you are, you give her some barley tea to cool off. You think it's stupid that he sent her over to settle the debt and you try to convince her that it's not necessary to do anything for you...

Akari: "Until my brother has paid the 500 yen, I'll gladly become senpai's property as collateral!" She said with unwavering determination.

Well that's just great... She is adamant to do something for you to settle her brother's debt, so you tell her to clean your room. She went to clean it alright, but not before she surprised you by hugging you tight and telling you you could "use her however you wanted"... Even her body. You tell her she doesn't have to go that far and that's when she finally starts the job you gave her. You come back an hour later and the room is even cleaner than when you first moved in. Seeing your approval, she says she's gonna clean everyday. This surprised you, but then she started to talk about rent, you ask her about it and she says she's gonna be living with you because she lied to her parents that she's gonna be living with her brother to study, but her brother is on vacation in Saipan, and that if you kick her out she'd have nowhere to go. Before you can say something she turns to the door and opens it.

Akari: "Ah, it's here." She brings in a suitcase My necessities are! She pulls out a futon from the suitcase Ta-daa! I brought my futon!