I want to find a manga where a character likes another character (but is too shy maybe) so to show them they like them they go to great lengths and do embarrassing things just to get their attention. I want it to end in actual romance please. I would prefer the boy to be the one that likes the girl at first but the other way around is okay too.

An example is there's this song about, a shy boy who likes a science girl and she doesn't really notice so he decides to become her guinea pig and that finally gets her attention. Something like that please. 😁

Funny that your example reminds me of a oneshot I read: Fukigen na Majou to Uchiki na Kedamono.

This one he embarrasses himself, but not because he loves her: Rensou Mode

I know that there is an other way around example of what you're looking for, but it's smut: Aisuru Hito

Another smut(ish) manga, but it's about a playboy being an baka in love with cold girl. Stroke Material

Hope it helps 🙂

I'm in idol hell T.T

Maybe Magico (IWAMOTO Naoki)
Aka the most sugary shounen I've ever read

My current top 3:
Fullmetal Alchemist
Pandora Hearts
3-gatsu no Lion