Nagi Amano, Hina Amano's younger brother born March 4, 2011, faced early hardship after their mother's death from illness and their father's prior absence. He and Hina lived independently in Tokyo, relying on Hina's income. This responsibility forced Nagi to mature quickly, fostering a deep awareness of his sister's sacrifices. Their close bond was forged through shared struggles. Confident and mischievous, Nagi displayed surprising social maturity for an elementary student, particularly adept with girls. This earned him a "playboy" reputation among peers and Hodaka Morishima's respectful "senpai." Beneath this charm lay genuine concern for Hina's well-being and a wish for her normal teenage life. He retained childhood innocence and curiosity, finding simple joys like junk food even in adversity. Physically, Nagi possessed black hair with a dark blue tint and blue eyes, resembling Hina but with a darker shade. Three years after the main events, only his height had changed significantly. In 2021, Nagi actively participated in events. Hodaka first observed him smoothly interacting with multiple girls on a bus. Later introduced as Hina's brother at their home, Nagi joined Hodaka and Hina in their "Sunshine Girl" business, assisting Hina as she used her weather-controlling ability to fulfill client requests, from personal favors to large events. Demonstrating loyalty and resourcefulness, Nagi fled with Hina and Hodaka after a police visit threatened Hina's custody. When captured and separated, Nagi was placed in a facility. He engineered an escape by swapping clothes with his friend Ayane during a distraction created by Kana. Free, he helped Hodaka reach the mystical tower to rescue Hina. During the tower confrontation, Nagi physically stopped Yasui from hindering Hodaka, shouting encouragement to save Hina. He later witnessed Hina's return and the rain's resumption from a police car. By 2024, Nagi maintained a close relationship with the Suga family. Keisuke Suga showed Hodaka a photo of outings featuring Nagi, Natsumi Suga, and Moka Suga, confirming his continued presence in their circle despite the ongoing rain.