Ok... im not talking about where one party just cant get good grades in school or one party is really slow. I mean low IQ wise, not just lazy or a bad student or a delinquent. Someone who isnt necessarily mentally retarded, but not the brightest person at figuring stuff normal people can easily figure out. I dont know if such a manga exists, but I would like to see it...

If what you're asking for is "someone" being naturally stupid then I think 90% of the shoujo heroines are like that. Most shoujo manga i've read have always had heroines doing bad in school (not because of laziness or just being a bad student). I guess you can just try picking a few shoujo manga though if thats not you're looking for then forget this reply was ever there lol

School Rumble is full of these characters =)

started with a kiss definitely fits your description....i havent read the manga but i saw the drama based on it.

fruits basket would be one example, I guess

Saboten no Himitsu
Special A
Strobe Edge
Ouran Koukou Host Club
Koukou Debut
Aishiteruze Baby

Quote from neha651

started with a kiss definitely fits your description....i havent read the manga but i saw the drama based on it.

I think you mean Itazura na Kiss 😀

Quote from Rainy Days

Special A
Ouran Koukou Host Club

Uh, both of these center around the smartest kids in school. Dense, but not dimwits.

as for a rec:
Akkan Baby

Practically half of all shoujo heroines.

Koukou Debut That girl is plainly close to being retarded...

♪MONSTARR~ will eat all your cookies and steal your bishies~♪ Φ_Φ

Quote from StarlightDreams

Practically half of all shoujo heroines.

Koukou Debut That girl is plainly close to being retarded...

But she never ceases to make me laugh. 🤣