https://www.dlsite.com/books/work/=/product_id/BJ589251.html
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This one is translated to english!

Fucked with a Giant Dick from Behind while on the Phone - A Serious Wife’s Filthy SEX

"I can't have an affair...!"
Maho is a housewife who is loved by her husband and leads a smooth marriage life. One day, at a cleaning shop she works part-time at, she witnesses the store manager having sex with one of his part-timers in the staff room.
She sees how violent the unfriendly store manager can be when he has sex, and while being shocked, she gets excited.
She has a desire to have an exciting sex like the ones in porn videos, but she has to hide her feelings.
She escapes and is ready to go home, but the store manager calls her and asks, "Did you see it earlier?"
Before she knows it, the manager has put his hands inside her panties and teased her wet pussy.
"The smell turns me on." She knows she can't do it, but her body is accepting the pleasure.
Did she start to realize her true desire...!?

Japanese version: https://e-hentai.org/g/2691276/82b9f1d27b/

EDIT: Fixed the blurry pictures of the first chapter

I don't know whether it's the author's doing or that this is actually incomplete. Because it's the second manga by this author that I see today that just ended abruptly as if a few more pages are missing.

Base +10

Now the censorship is on par with mainstream non-porn manga.

Base +7

What's up with the blurry pictures?

Base +6, Cloud kun +8