Manga where the naive/idealistic/selfless typical boy with a harem pay the price for his idiocy and eventually got crushed by the protagonist?

[sonhot]

Just as the title said, i want to find a manga where the typical harem boy character got crushed mentally, his harem member taken by his rival the protagonist (both should be male if possible). The harem boy should possess most if not all of these trope (naive/idealist/selfless/kind/indecisive/overbearingly humble/shy/flustered...) and his rival the protagonist who act alone at first would be mostly the complete opposite (few words/calm/collected/proud but not arrogant/humble but not shy/...) they both would be on the same side fighting against some comically evil human/alien/tentacle/god...not really important here since the story should be focusing on the protagonist victory over the villains all the while humiliating and taking harem member from his rival at the same time. Sorry for my engrish lol.

 

[sterven]

Tanaka is the only one I can think of that vaguely matches this description.

 

[sonhot]

I guess this itch is hard to scratch after all. I tried to search for a while but only resulted in a few novels and no manga that fit. About this Tanaka manga, i heard about it long ago but hesitated to read since all the comment state that the protagonist was pretty bad, wonder how bad he's actually is so maybe anyone could give me some spoiler? Anyway thanks @sterven for the recommendation.