Kuchibiru Tameiki Sakurairo 1 /くちびるためいきさくらいろ 1

The incredibly popular series by Morinaga Milk! Nana is deeply hurt by her best friend Hitomi choosing another school to attend. But when she learns why, Nana realizes that she and Hitomi have the same “not friend” feelings for one another.

This is the first volume of the Japanese edition. For the English edition, check out the listing for Kisses, Sighs, and Cherry Blossoms Pink.