Masked Fate: Beautiful Naked Angel (2009)

Kizuki takes a job teaching painting at a free school, and his target is Yoichi, a student and guard. One day, Kizuki invites Yoichi and her friend Tooru to her home and asks them to be nude models. Youichi is confused by Kizuki's desire to film her in a fundoshi and masturbation scene, but he shows Yoichi his gas mask and combat uniform and tells him about his life in which he has lived wearing a mask. Yoichi, who is not disgusted by Kizuki's blow job, begins to think that he wants to be true to his sexuality...