Nijiiro Days chronicles the vibrant lives and romantic entanglements of four high school boys: Natsuki Hashiba, a dreamer harboring delusions of love; Tomoya Matsunaga, a narcissistic playboy with multiple girlfriends; Keiichi Katakura, a kinky sadist who always carries a whip; and Tsuyoshi Naoe, an otaku with a cosplaying girlfriend. When his girlfriend abruptly dumps him on Christmas Eve, Natsuki breaks down in tears in the middle of the street and is offered tissues by a girl in a Santa Claus suit. He instantly falls in love with this girl, Anna Kobayakawa, who fortunately attends the same school as him. Natsuki's pursuit of Anna should have been simple and uneventful; however, much to his dismay, his nosy friends constantly meddle in his relationship, as they strive to succeed in their own endeavors of love.