The Series

"Fuuko Kameyama is a bright and energetic girl. One day, the cool-headed Ichi and the mischievous Daiya move into the apartment above hers. Fuuko's first impressions of them are awful. What will become of Fuuko's high school life now that these two guys also attend her high school?" -- from volume one's back cover

Parfait Tic is a shoujo manga written and illustrated by Nanaji Nagamu. It ran in the comic magazine, Magaret, from 2000 to 2007. There are 22 volumes in this finished series. It is currently unlicensed in North America. Scanlations of this series in English can be found online (but not here).