Negative Twin-Tower!

Hyoudou Kaname and Shishido Makoto are two abnormally tall (over 180 cm!), sharp-eyed high school girls. That, in addition to Kaname's emotional instability and violent outbursts, has instilled a fear of the two girls in all their classmates. But, though they're bad at dealing with people, they are actually normal girls. They just want to hang out with friends, have boyfriends, and enjoy high school like other girls, but they fail whenever they try. If they don't get discouraged and continue to work at getting to know others, will a day come when they can smile and be happy? It's a high tension school comedy drawn with a unique style and tempo.

(Source: MangaHelpers)