The wife of this young man is about to have birth, so after a period of abstinence, he has quite blue balls. One day, he discovers Sister-in-law Meguri is going through pretty much the same, as she is masturbating alone in the bed, but doesn’t make a move for now. Not long after the situation is reversed, as it’s Meguri who catches him masturbating alone in the room, and she cannot handle anymore her hornyness thus they collide in the hallway.
The story might sound a bit weird but it was developed nicely, actually. And when the sex scenes finally arrive we get to admire Meguri in all her voluptuousness, which is pretty good tbh.