Maki was living a normal and peaceful life with her husband and son. - However, one day, the relationship between mother and child changes completely when her son witnesses the couple's nightly activities. - My son asks his mother to have sex with him every time he sees something, saying, ``I can't stop getting an erection because I saw my mother's erotic appearance!'' - Maki complies even though she knows it's not right. - In the end, the two of them cross a line that they should never cross. - "What is this...my son's dick feels so good..."