Kaho is a college student who is new to relationships and wants a boyfriend. One day, her brother-in-law Ryota kisses her and says, "Isn't it good with me? and her brother-in-law, Ryota, kissed her!　Since then, Kaho can't forget that kiss and spends her days in agony. She finds herself thinking about Ryota all the time...?　A kissing brother and sister-in-law!　Forbidden love with a mocking brother-in-law!