Nijiiro Days (MIZUNO Minami)

From Freewheeling Scanlations: Natsuki is teased for being a hopeless romantic, Keiichi disguises his sadism with an angelic grin, Tsuyoshi is an otaku who can't read the air, and Tomoya is a frivolous playboy who likes his archenemy. The rainbow-colored story of (sometimes dubious) friendship and (mis)adventures in love of these four boys who spend their daily high school life by having fun starts when recently-dumped Natsuki received a pack of tissues from a girl wearing Santa costume in the streets on Christmas eve.