From JShoujo Scans:

Little Rin Fujiwara hated her own face a lot. It was not until her sixth birthday that a make up box she got as a present changes her perspective completely. In front of the mirror, Rin would play with the make up, which becomes like a magic that makes her stronger. Rin believes make up can change both appearance and heart, because it gives the confidence a girl needs.
Years later, Rin attends her first high school year. She decides to help other girls there to become pretty as well, using her make up box. Rin, hidden under the identity of Ageha, a legendary make up stylist, with help from her classmate Kisaragi, who has to hide his real identity by crossdressing as a woman, is willing to do magic in front of the mirror and change girls "just like when a caterpillar transforms into a butterfly". How to meet Ageha and have her make you more beautiful? Easy, just write your name and class on the butterfly card and put it on the bulletin board on the third floor. Ageha will come for sure, so what are you waiting for?

Note: Extra chapters in vols. 3 and 5 weren't scanlated.