it's a chapter in a manga (collection of oneshots). and i think it's not the first chapter.
Here's what I remember:

the salaryman (the one wearing suit) is taking driving class. He found that the instructor is a divorcee, and is a fan of Kinnikuman (or some manga/anime that is a parody of Kinnikuman, I think). He won an original character contest when he was a kid (his original character was Minotaurman, I think). As the salaryman is also a fan, the two hit it off really well. It then revealed that they are both lonely, so they started to feel something about each other and then proceed to fuck.
It was sort of comedic, and the art is a bit bara, if i remember it right.
Anyone know what manga is this??
Thank you so much in advance~

It's by the artist KIJIMA Hyougo but I can't remember which manga exactly contains this oneshot

Thank you Psych~♥
Hmm,,, so I was right! I've had a feeling it was one of her works,,, but I couldn't find it when I went through some of them earlier. I must have missed it. I guess I have to go through her mangas one more time and more thoroughly~
Again, thank you so much!

Wait, I'm sorry, it was by Psyche Delico and not Kijima D:
2nd chapter of Kizudarake no Airabuyuu
Sorry again, and good read :3

thank you so much,, actually I had believed that it was by Kijima Hyougo even before I asked this here, so your earlier reply convinced me that I was right,,, hahaha,,, so it was actually by Psyche Delico,,, no wonder I couldn't find it when I went through Kijima's works,,, hahahah,,,
okay, thank you very much!