Koshiro and Nanoka fall deeply in love, then discover they are the children of their divorced estranged parents - making them brother and sister. How will their relationship turn out?

After a 27 year old man has chance encounter with a fifteen year old girl, they discover that they are actually brother and sister. They were separated over a decade before due to their parents divorce, but now she is coming to move in with him and their father. Will they fight their desire for each other or give into incestuous desire?—Anonymous

Koshiro Saeki, a 27-year-old who has just broken up with his girlfriend, meets Nanoka Kohinata, a 15-year-old going through the same predicament. The two form a mutual bond and fit well together... Later, Koshiro's divorced/single father Zenzo Saeki informs him that his sister, who left with her mother when Zenzo divorced, will be coming to stay with them: Nanoka! Koshiro is horrified and tries to suppress his feelings for his sister, but she takes it all naturally and devotes herself to winning Koshiro's affection. What will become of the two lover-siblings?—Q. Leo Rahman