To you guys who say NTR, I doubt it. The guy to the front was wearing school uniforms and the title of the manga disagrees with the idea that this woman is a wife.
@TheMarksman
>She's wearing a ring
>it's on her left ring finger
>Protagonist's hand is sweating
>implied by title he's not the husband
Regardless if waving man is husband, son, or neighbor. It's safe to assume what we are looking at is a small form of cheating.
I say small, because we get no more contextual information to imply anything beyond her sending updates on underwear. Maybe thats how she gets her kicks with her husband away? Maybe they're fucking? No one knows!
I was about to say that this has to be one of the hottest so far, then I saw the ring and everything clicked. So cheers to the guy who says the other is a student, hope you're right and she's just a widow