Manami, the class representative, is a little naughty. During class, she fantasizes about naughty things and masturbates without being noticed. When she gets home, she rubs her nipples. I'm really a naughty girl. I wonder if the boys in my class will moan when their nipples are touched like mine? Manami, who is interested in boys' nipples, invites fellow class representative Hisamichi to her house to touch her nipples. A secret between the two of them. Seeing a man who feels pleasure from her nipples, Manami gradually begins to develop a slutty Kokoro...