Fuufu Koukan: Otto yori Sugoi Kongai Sex

I hear my beloved wife's moans through the sliding door as she's having sex with her affair. Meanwhile, I'm also having sex with my friend's wife and letting out my sperms...
(Source: Coolmic)
Notes:
- Includes 1 extra chapter.
- Originally serialized as a web manga under the title Fuufu Koukan: Ichido Shitara Modorenai... Otto yori Sugoi Kongai Sex (夫婦交姦～一度シたら戻れない…夫よりスゴい婚外セックス～).
- Simultaneously released in long-strip and traditional formats, with each chapter split into 3 ‘episodes’.