Sumire, who had been dating her worthless ex-boyfriend Tsuyoshi. Tsuyoshi was a typical delinquent loser who always hit her up for money, cheated, and didn't use protection. After years of being together, Sumire finally managed to escape from Tsuyoshi. Now she is living with Takao, a kind and decent boyfriend, on the premise of marriage. However, after seeing Sumire with Takao, Tsuyoshi tried to pursue her again.
