Mana is a beautiful girl with excellent grades. Unfortunately, due to difficult circumstances involving her parents, she works as a private tutor to lessen the burden on her parents as much as she can, leaving no time for a boyfriend. After a lesson with Taichi, one of her students, bad weather and dangerous driving conditions make it impossible for her to safely return home. Mana is stranded at Taichi's house but is invited by his father to stay the night in a spare room. She discovers that Taichi's mother passed away years ago, and his father spends every night grappling with loneliness. As a result, he is no longer able to control his urges in the presence of a cute high school girl in his home. Taking advantage of Mana's desperation for money, he asks that she act as his "girlfriend" for the night in exchange for three times her usual pay.