Nozomu Nanashima is a second-year high school student and one of four boys who develop feelings for Kae Serinuma after her dramatic weight loss. Frequently called by the nickname Nana, he is the older brother of Kirari Nanashima, whom he adores and actively cares for. Nozomu has green eyes and blonde hair that falls to his ears. His name is written with the kanji for the number seven, which leads Kae to pair him with his best friend Yusuke Igarashi under the ship name 5x7.

Nozomu is generally cheerful, emotionally expressive, and open with his feelings, which sets him apart from some of the other love interests. He is protective of Kae and will step in if anyone tries to harm her, showing that he considers her someone important whom he does not want to give up on. This protective side emerges even unconsciously: when he once came down with a fever, he climbed on top of Kae and kissed her in his sleep, marking her second kiss. His loyalty extends to his friends as well, especially Igarashi, whom he has known as a best friend since middle school.

Despite being rivals for Kae's affection, Nozomu and fellow admirer Hayato Shinomiya start their relationship as competitors. Nozomu’s affectionate and caring nature is most visible in how he treats his younger sister, whom he takes care of with great devotion. Over the course of the story, Nozomu matures from a simple admirer into someone who actively protects and supports Kae while maintaining his close bonds with the other boys. He does not have any supernatural or extraordinary abilities; his notable traits are his warmth, protectiveness, and unguarded emotional honesty.