The incest tag on the raw is wrong. Bo-kun isn't related to Fumei.
Gotta love a classically beautiful, curvy MILF! She'd be right at home on a renaissance painters canvas. There's not nearly enough hentai of these thick MILFs. I'm so grateful I found Sensei's work. Look forward to more translations.
As for Fumei, there's something delightful about how hard she gets fucked and how much she loves it. Despite being used roughly, she always presents as being in control of the situation. That's another thing that's great about chubby chicks, they're super soft and durable, so they can take a hell of a pounding without being hurt.
This is pretty damn close to netorare. In fact I'd say it is. MC knows he's not her only man, but he wants to be, he's jealous. She even tells him she's about to be fucked by another guy, something he would rather not have happen.