Quote from Saexel

La Corda D'Oro - The double personality guy is sorta leaning more on side character, but there are moments still the same.

do you mean Yunoki?
'cuz if you do, then yeah, he's so mean to Hino! and then he's nce to everybody else

Quote from lambchopsil

A GUY, not a girl

oops I misread lol

known as Lucifer / Killy69 / Guts / L41n / Lain Iwakura / Schrö.

Quote from smichal

Well... i dont know if its exactly what you want ,but you could try [Ranma 1/2](http://www.mangaupdates.com/series.html?id=1049). The guy changes to a girl when he touches cold water, and back to a guy when its hot.
I dont think you can expect to get a "good" romance out of it (after all thats not
the point in it) but it can offer you much laugh and relaxation for a long...long time.
Even after so much time, nothing can beat a classic 😀

It's better than Ashita no Yoiichi. But even if Ranma 1/2 is good, I don't think it's what this thread is looking for.

This signature was recovered from Hades to serve in my rotting armies.

Dragonball, Goku is bipolar ha ha. No I'm kidding.

I'll second Imadoki.

Kare Kano to some extent, though it's much more the girl who has a split personality the guy still has one to some extent, its much more prevelant in later volumes though.

Trigun has it's moments. Though in my opinion the anime was much better than the manga.

KARE KANO... can't believe ppl missed tht.

H2O man! xD

Ijiwaru Shinaide! works... there are a TON of smutty ones with guys like that, too, come to think of it, but I dunno if you want smut. I second La Corda d'Oro, though, as well as Imadoki.

poof "SHOUJOMAN IS HERE!"
Just Lynz, drop the -ajw

Cutie Boy matches it perfectly

Megane Ouji
Cutie Boy
Show Princess

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