Ga-ma-n Dekinai♥

Minato is a clumsy high school girl. When she went to the infirmary to lie down, she found a naked guy, and he kissed her! The guy is Chihiro, a tenth grader who is one year younger than she is. Minato is very interested in him, but he already has a girlfriend. Minato plans to give up, but...?

(Source: RebelliousArt)

Included one-shots:
Volume 5: Amai Yokubou (Sweet Desire)
Volume 6: Only One: Tatta Hitori no Taisetsu na Dareka
Volume 7: Fake Lover