Azuma Kenji

In reality, Kenji has let Marina have sex with other men because he cannot get her himself to make reach her such a high level of orgasm.

In Kashidashi Tsuma, Marina no "Netorase" Houkoku Binkan Tsuma to Zetsurin Daigakusei, Kenji convinces Marina to have sex with Hiroto, a college student. Although she is reluctant at first, she agrees to his request. Both Marina and Hiroto meet up to have sex, while Kenji fantasizes about her being pleasured by another man. The following day, Marina recounts her sexual experience with Hiroto to Kenji while fucking him. She agrees to meet with Hiroto again.

After fucking Hiroto a second time, Marina comes back home tired, at first unwilling to talk about her experience with Kenji. However, she gets naked later that night and takes pleasure in teasing him about how good Hiroto felt, causing Kenji to ejaculate powerfully. They even invite Hiroto over for dinner one night; during this time, Kenji sees Marina shamelessly flirt with Hiroto, even hearing her kiss him before he leaves. This leaves Kenji troubled, as they appear to be far more intimate than Marina has made it seem like previously.

Kenji’s suspicions that Marina is not being entirely truthful with him grow, given that she deflects several of his questions regarding how good Hiroto is at sex, opting to tease him instead. One night, Kenji sneaks over to the love hotel where the two of them are staying, and overhears them outside their room. They are audibly having sex, and Marina comments on how good it feels when Hiroto cums inside her so much. Kenji calls Marina, who lies and says that they haven’t started yet. She orgasms before hanging up, making lewd noises that Kenji has never heard her make before when they have sex. Unfortunately, Kenji is forced to flee the hotel, lest he get caught peeping.

Marina and Hiroto go on a trip to a hot springs resort, and Kenji listens to them fuck over the phone. He hears Hiroto cum, and Marina reveals that he came inside her pussy unprotected. She tells Kenji that she has to get Hiroto’s penis ready for another round, and he hears a splash as the two of them dive into the hot springs completely nude, before the phone hangs up. This turns on Kenji so much that he ejaculates six times.

When they both return home, they talk about their time together with Kenji, revealing that they had hot and steamy sex the entire trip. Kenji also suspects that they are holding hands under the table, turning him on so much that he excuses himself. From the other room, he hears both Marina and Hiroto kissing each other, while the latter fondles the former's breasts. Kenji jerks off and cums all over the floor.

Kenji then suggests that Marina invite Hiroto to their house to have sex, under the pretense of convenience (though what he really wants is to see them fuck). Hiding under the bed, he hears them enter the bedroom, strip off their clothes, and listens as Hiroto plows Marina on top of the bed. The two are far more intimate than Kenji expects; they kiss frequently and talk lovingly to each other while fucking like beasts. Hiroto then blows a huge load inside Marina’s pussy, causing her to cum, their fluids leaking on the floor. Hiroto (who sounds far more bold) suggests that they take a break after that hot fuck-session, and the two leap onto the bed to rest. Coming out of hiding, Kenji sees both of them cuddling completely nude under the covers while fast asleep, looking like a married couple. The true nature of their relationship made clear to him, he hides in the closet as they start to wake up.

While Kenji is not especially impressive when it comes to sex, his sex drive is shown to increase drastically whenever his wife is fucking another man. When Marina teases Kenji about how good Hiroto was at fucking while giving him a handjob, Kenji is so turned on that cum sprays out of his penis like a geyser, the amount shocking even Marina.

At the end of Marina no "Netorase" Houkoku 3 Case. Moto Kareshi & Binkan Tsuma, after Marina's rape he apologizes to her for having forced her to sleep with other men even if she tells him that it's also her fault that she never refused.