Synopsis
Kagami Yuuki has managed to become a scholarship student in a high-class high school. Unfortunately, thanks to his gender-ambiguous name, the teacher Kakinozaki Ayana has registered him as a girl! It's apparently an uncorrectable mistake, so now Yuuki must live in the girl's dormitory of his new (co-ed) high school.
At least Ayana's willing to take responsibility for her mistake; she volunteers to be his roommate. As one would guess, he and Ayana must make sure none of the other girls in the dorm find out he's actually a boy. Therefore, except for when he's in his classes, Yuuki has to cross-dress, or else both he and his teacher will be kicked out of the school and dorm!
Spoiler for Kagami, Yuuki "MC very LB":
After finally got into Hourin Academy with a scholarship, Yuuki finds him self it the predicament of being assigned to the Girls' Dormitory due the mistake of Kakinozaka-sensei, so now he must disguise himself as a girl to avoid being expelled.
Spoiler for Kakinozaka, Ayana:
In charge of the new students room assignment, She is the clumsy teacher that put Yuuki in his particular predicament, assigned him to the girl's dormitory, by assumed he was a girl.
Now, she started living with him in the same room in order to prevent Yuuki been expelled, but it seems that she would be the biggest problem...