On her way to Morino University, Konoka struggles to hold her bladder on a crowded train, leading to an embarrassing accident in front of her teacher, Kaneko-sensei. When he offers to help her clean up, the encounter quickly turns sexual, leaving the two with a scandalous secret to keep.
Naho visits her cousin Tatsuya on weekends for tutoring, but their sessions quickly turn into secret sexual encounters. Despite her initial hesitation, Naho discovers her own arousal as Tatsuya introduces her to new pleasures, culminating in their first time having intercourse. By the end of the visit, Naho finds herself longing for these forbidden weekends and the daring games they play.
Inoue Emi, a frail student, maintains a secret sexual relationship with her teacher in the school infirmary. While she enjoys their daily encounters, she begins to experience a strange, intense throbbing in her chest that signals her deepening obsession with him. Despite her friends' curiosity about why she is always staying late to "assist" the teacher, Emi remains devoted to their hidden passion.