Nagisa Amano, nicknamed Nagi, is the younger brother of Hina Amano. Born March 4, 2011, in Tokyo, he lives with his sister following the death of their mother, Megumi Amano, from illness. Their father is absent, likely deceased or divorced before 2020. Hina supports them financially, and they live independently under difficult conditions. An elementary school student during the main events, Nagi displays notable confidence and maturity beyond his years, especially in interactions with girls, earning him a reputation as popular or "playful" among peers. This trait prompts Hodaka Morishima to address him respectfully as "senpai." Despite this outward persona, Nagi possesses a caring and self-aware nature, recognizing Hina's sacrifices and expressing a desire for her to have a normal teenage life. He first appears when Hodaka observes him smoothly interacting with multiple girls on a bus. Later, Hodaka formally meets him at Hina's home, where Nagi interrupts their discussion about the "Sunshine Girl" venture. He becomes involved in their weather-clearing business, assisting with client requests ranging from small events to corporate functions. During this time, he demonstrates loyalty to his sister and Hodaka, participating in jobs like clearing the sky for Fumi Tachibana's personal ritual. Nagi also engages in everyday activities like soccer, scoring a goal during a school match observed by Hodaka. Afterward, he questions Hodaka about his romantic feelings for Hina and offers relationship advice, underscoring his perceptiveness. When a police officer threatens custody, Nagi flees home with Hodaka and Hina. The trio evades police through worsening weather, including snow, until apprehended at a hotel. After Hina disappears, Nagi is placed in a facility but orchestrates an escape by swapping clothes with his friend Ayane while another friend, Kana, distracts staff. He rushes to the abandoned building where Hodaka attempts to rescue Hina, physically intervening to stop Yasui from obstructing Hodaka while shouting for him to save Hina. Three years later, Nagi maintains a close relationship with the Suga family, appearing in an outing photo with Keisuke Suga, Natsumi Suga, and Moka Suga. His appearance changes slightly through increased height, but his core personality traits remain consistent. His surname, Amano (天野), combines the kanji for "sky" (天) and "field" (野), while his given name, Nagi (凪), means "calm," reflecting the film’s weather motifs.