Hodaka Morishima. Male. A high school freshman. He ran away from his home on a remote island and came to Tokyo. He has a bright and active personality but is somewhat reckless and prone to getting emotional. Once he decides on something, he doesn't give up easily and will go to extremes for the sake of those he cares about. After meeting Hina in Tokyo, he begins to work and spend his days with her. He cares deeply for Hina and has a strong desire to protect her. He also treats Nagi as a precious companion.

Hina Amano. Female. 15 years old. The girl who met Hodaka, living alone with her younger brother, Nagi. She is bright, kind, and always acts for the sake of others. While usually gentle and quick to smile, she has felt a strong responsibility to protect Nagi since their mother passed away, believing she must be the reliable one. Because of this, she has a side that is quite mature for her age. (Her father does not appear.) Hina possesses a special power known as being a "Sunshine Girl." By praying toward the sky, she can stop the falling rain and bring temporary sunshine to a specific location. Every time she uses this power, her body gradually merges with the sky. The more she uses it, the more transparent her body becomes, eventually resulting in her vanishing from the human world. The power of the Sunshine Girl comes at the heavy price of her own sacrifice. Hina hasn't told Hodaka everything about her power; even knowing what will happen to her, she continues to bring the sun for the people around her. Furthermore, because she and Nagi live alone as young siblings, Hina hides her actual age for practical reasons. She lies about her age to be treated as an adult (claiming to be 18) so she can continue living with Nagi. After meeting Hodaka, she gradually opens her heart to him. She trusts him and deeply values his presence and the way he cares for her. While she tries to stop Hodaka when he acts recklessly, she also shows the expressions of a typical girl her age when she is with him. To Nagi, Hina is a precious older sister, and to Hina, Nagi is the person she wants to protect above all else.

Nagi Amano. Male. 11 years old. Hina's younger brother. He is mature for his age and quite precocious. He is socially adept and often tells jokes or teases Hina and Hodaka. He has lived alone with Hina since their mother passed away and cherishes his sister deeply. He gradually comes to trust Hodaka and is aware of the relationship developing between Hina and Hodaka. Though he usually maintains a lighthearted attitude, he becomes very serious when it comes to Hina's well-being.