Marin-chan, who is one year older than me and a childhood friend, is an excellent student, and I often went to her house to get tutoring. When I told her that I had recently become interested in sm play, she said, "Shall we try it...?" Yay! First, let's play bondage with a cotton rope. When I fixed her in an embarrassing position, there was already a stain on her underwear... When I used a brush, the erotic liquid overflowed more and more. I was also getting excited, so I involuntarily stuck my dick in her mouth! Is this what irrumatio is? She looks like she's in so much pain! It's unbearable! It seems like my sister doesn't mind it either. Is this what awakening to masochism is like? Maybe I have a talent for this. ...I decided to train her as a masochistic pet.