tldr: You actually see the characters grow
I’ll do my best to not have any spoilers.
And yes, the title in english would be “Masturbation Master Kurosawa”
I actually remember trying to get someone to read this manga after I finished reading it and they got really angry at me for forcing them to read hentai. THIS IS NOT A HENTAI DOUJIN. I got really pissed at them for only reading the title and like the first few chapters where the MC was still giving us some background on his “hobby” and immediately making a conclusion that it’s shit. Which is kinda funny since the whole manga is practically about redeeming one’s self and actually has a character whose appearance definitely doesn’t match their real selves.
WHY I LOVE IT
Despite the drawings looking average, I found myself feeling the same way the MC did (no I do not go inside girl’s bathrooms or jerk off that much) and managed to get myself immersed in its story. I definitely cried at some points in the manga and looking back, I’m happy I did as I can’t experience that for the first time again. Also it’s hilarious at some times, read this in my early college years and all I remember now are the hard hitting parts so I can’t really recall all the funny parts but they’re definitely there and they give a nice break from all the “feelings” you’ll be feeling.
And the characters, man. I swear you get to watch them grow before your very eyes. Before reading this, I would just read/watch whatever just to overcome my boredom but after this I started seeking better stories with better character growth, or better plot, or just better everything. But this still manages to stay in the top part of my list and that really impresses me.
If you finished reading this I would recommend reading Molester Man next since it’s made by the same guy. Yes that’s one hell of a title but it’s also one hell of a ride, just like Onani Master. Although I recommend that you would be kinda familiar with imageboards before reading it.