Yuurei to Boku

Yamato, a male student, is troubled by recurring "dreams." Every time he falls asleep, mysterious tentacles appear. His nipples are teased, his genitals are prodded, and eventually, even his rear is violated... Despite the fear and disgust, his body, against his will, feels increasingly good. Attacking him relentlessly during class, in the infirmary, anywhere—what is the true nature of these assaults?

(Source: Fusion Product, translated)

Included one-shot: Neko to Janken