If the title and the tags didn’t clue you in, this is a NTR doujin. The setup is pretty standard for the genre: a guy gets confessed to by his junior on his graduation day, they end up dating, the girls turns out to be hotter than she seemed at first, they finally have sex, but oh no! Her classmate took a photo of them going into a love hotel and is now going to coerce her into cheating on his boyfriend with him. You know the drill.

It’s not the setup, but the execution that’s exceptional here: the art is great, the girl is incredibly hot (just look at the cover) and the corruption proceeds at the ideal pace: not so fast that it ends quickly, nor so slow that the girl never stops resisting.
*All characters depicted in this work of fiction are adults, regardless of their visual representation or textual description, and are not based on any real person*