Mako Momozono's boyfriend suddenly breaks up with her because she wouldn't do it with him! After she drowns her sorrows in booze, Mako sits down on a bench to clear her head. She ends up falling asleep when Arata Shichimiya, her sister-obsessed brother's friend, happens to pass by! While she's still passed out, Arata carries Mako to his place to make sure she's okay... The next day she wakes up to a room she doesn't recognize. Mako jumps awake and immediately sees that someone's next to her. She has red marks on her, her hips ache... and she's naked! Mako and Arata become friends with benefits, but there's a twist...