Of course, I can't talk about shonen manga without some sort of horny nonsense, and boy does this one live up to both parts of that phrase.
MAYO CHIKI!, based on the light novels by Hajime Asano and illustrations by Seiji Kikuchi, with art by NEET. First published in 2010 and first published in North America in 2012.
PLOT:
Sakamachi Kinjiro is a teen boy with a serious problem. He's got a terrible fear of women which tends to manifest as sudden, involuntary nosebleeds. Through a series of accidents, he discovers that the butler serving the resident rich girl Kanade Suzutsuki is secretly a girl. Said butler, Subaru Konoe, is all too ready to kill Kinjiro for uncovering her secret but Kanade has a better idea. In return for keeping Subaru's secret, Kinjiro will go on dates with Suburu to cure his gynophobia. Misadventures ensue, and Kinjiro is going to need to man up fast if he (and his blood pressure) are going to survive.