The way of making a Prince(2005)

Oujisama no Tsukurikata

Yuiri is a first year highschooler and the granddaughter of the principal. She attends Angelic Garden Highschool where she meets 4 handsome devils. It is her job to try and make these devils into angels. While in school, she goes under cover also as her brother Hairi. Can she persevere against these devils?

(Source: Shoujo Manga Maniac)