Nijiiro Days tracks the vivid lives and love stories of four high‑school boys—Natsuki Hashiba, a romantic dreamer; Tomoya Matsunaga, a self‑confident playboy with several girlfriends; Keiichi Katakura, an eccentric sadist who never leaves his whip behind; and Tsuyoshi Naoe, a devoted otaku whose partner cosplays. When his girlfriend abruptly leaves him on Christmas Eve, Natsuki collapses in tears amid the bustling street and receives a handkerchief from a girl dressed as Santa Claus. He immediately falls for Anna Kobayakawa, who serendipitously attends the same school as him. Natsuki"s pursuit of Anna should have been straightforward, yet his friends—each chasing their own romantic goals—constantly intrude. Their interference ranges from teasing to unsolicited advice, turning a simple courtship into misunderstandings. Meanwhile, Natsuki struggles to balance his feelings with the drama. All the while, classmates watch with curiosity.