Try Tenshi na Konamaiki. I'm not going to explain too much and spoil anything. =D

Adding:
Nousatsu Junkie

Tenshi na Konamaiki doesn't fit the criteria, though thank you anyway. Nousatsu Junkie doesn't seem to fit the criteria either; could you confirm that he falls for a girl disguised as a guy?

Quote from romantiscue

@Superfreak: Bara no Maria isn't listed as a gender bender. Could you explain why you think it fits the critera I was looking for? curiousiscurious

Thanks for your suggestions everybody 🙂

I think that Superfreak suggested Bara no Maria because Maria's gender is something of a mystery...according to some people who have read the novel, Maria is a boy, but in the manga the only thing Maria says is "I'm not a a little girl" and "I'm gonna get banged" so she may be a girl, and the guy that likes her doesn't really care for her gender though....

i think Power!! fits the description right?
😃

Thank you for clarifying that, catandmouse!

happyginger: It's been suggested before, but thank you any way.

On another note, since it's appeared on the 'False Shounen Ai' list, can anyone confirm/deny that 07-Ghost has elements of what I'm looking for?