I guess Naporitan wanted to mix things up a bit after so doing so much regular netorare, but just a bit, Naporitan only reversed the infidelity dynamic; the protagonist is the one being taken.
Shun has been dating Mirika for two months, he wants to lay her down so bad but Mirika keeps refusing this next step for some reason, she seems like Shun so why is that? Whatever reason may be it is making Shun lose his wits, he wants to have sex so badly! Then there is Mirika's mom Natsuno, a beautiful gyaru milf, a single mom who still looks so hot, damn, Shun is burning with desires, he couldn't help but masturbate his frustration away... which gets him caught by Natsuno, oh shit! However, Natsuno too is pretty pent-up as well, and that naturally means her daughter's boyfriend will do the trick; Shun and Natusno lose themselves to pleasure with Mirika left by the wayside.
Why is Mirika pushing Shun away? Poor girl is filled with desires too, she wants to lay with Shun so bad... but she has inverted nipples, she fears Shun will hate how her boobs look, poor girl, THE END.