These are the main characters of the series.
Saku Ooyagi (大八木 朔)[]
Saku Oyagi is the main protagonist for this story, who grew up traveling around Japan due to his father constantly changing jobs. Saku loves to read books and can often be seen reading, whether it be on the bus, at school, or at home. He generally likes to stay indoors and read, but after joining the Astronomy Club, he starts to enjoy going out and stargazing or participating in other club activities. As Fumie notes, his writing skills are top notch, making him better suited for the Literature Club. While he is constantly annoyed by Mihoshi, he does enjoy her company. However, because of how Mihoshi shows up to his class a lot, many of his classmates believe that they are dating (much to the dismay of Hime and Saku). In the anime is hinted that he likes Mihoshi.
Sayo Yarai (佐用矢来)[]
Sayo Yarai is a calm and intelligent girl who is in the same year as Mihoshi and is also a member of the Astronomy Club. Her family runs a Buddhist temple.
Hime Makita (蒔田 姫)[]
Hime Makita is a girl in the same class as Saku, whom she has a crush on. After Saku joins the Astronomy Club, she quickly follows suit so as to spend more time close to him and to get to know him better. She had originally met Saku briefly on the bus before taking their entrance exam for the school, and was surprised to see him again in her class. She is generally a calm girl but is known to get jealous of Mihoshi when she is sticking close to Saku. Though she has a crush on Saku, she is easily put off by other guys trying to make advances on her. Hime's hair gets frizzy in high-humidity weather, and her sister can use this trait to gauge the humidity in the air.
Masashi Edogawa (江戸川 正志)[]
- Voiced by: Reiko Takagi
Masashi Edogawa is one of Saku's classmates and friend, and while he often takes part in Astronomy Club activities, he is actually a member of the Photography Club. He enjoys hanging around the Astronomy Club because of Mihoshi, Sayo and Hime, whom he sees as all very attractive, and is jealous that Saku is surrounded by beautiful girls. However, he also enjoys astronomy and actively participates in stargazing events. His photography skills tend to come in handy in promoting the Astronomy Club.
Takeyasu Roma (路万 健康)[]
Takeyasu Roma is the president of the Astronomy Club. He has always had a poor constitution and is generally very weak and often spits up blood or passes out after doing something strenuous. He has an intense love of astronomy, akin to Mihoshi's own enthusiasm. After graduating, he goes to college with Ayumi Oumi, a girl with the same passion for astronomy as him, and who has a crush on him.
Fumie Kotozuka (琴塚 文江)[]
- Voiced by: Ami Koshimizu
Fumie Kotozuka is the Student Council president and is a member of the Literature Club, though still often takes charge in club events despite not being the president. She notices how Saku also enjoys books and reading and has invited him to the Literature Club on multiple occasions. She admires Saku's writing skills and has an interest in him. She feels that the Astronomy Club and its members are not what a club should be and is generally not favorable about their activities. She has known Mihoshi for several years, but feels animosity towards her. She has terrible eyesight and has trouble distinguishing objects and people without correction. She seems to have some kind of feelings towards Saku.
Mihoshi Akeno (明野美星)[]
Mihoshi Akeno is a cheerful girl who is one year older than Saku, though has a tendency to act childish. She is very enthusiastic about, and has a strong love for, the universe; a trait passed down from her late father. She has always enjoyed going outside and stargazing or doing other activities, and would usually take Saku along with her, often against his will. She is thrilled to be reunited with her childhood friend Saku and convinces him to join the Astronomy Club at school.