Long blonde hair, green eyes. Female, 16 years old. First person: I (polite/casual). Second person: -san, -kun. A high school freshman. She is short and has a somewhat youthful appearance. Bright and always looking for efficiency. She is close friends with university students Nagi Arato and Yoko Imari, often going to the mountains with them to find minerals. She is also close with her classmate Glass Seto and childhood friend Aoi Kasamaru. She calls Nagi by her first name and refers to Seto and Yoko by their surnames. Please look up the series for more details.

Long black hair, black eyes. Female, 24 years old. First person: I (polite). Second person: you / first name only. Cool, mature, and reliable. She is tall and gives a sophisticated impression. An expert on gemstones, she spends her days researching at the Maeshiba University Faculty of Science Mineralogy Lab. She has her own car and drives everyone to various locations like mountains. She is close with Ruri Tanigawa and Glass Seto, often heading to mountains and rivers to search for ores. Yoko Imari is her junior and they are on good terms. Please look up the series for more details.

Short brown hair, brown eyes. Female, 21 years old. First person: I (polite). Second person: -chan, -kun. Mature but somewhat airheaded and clumsy. She is tall and looks like a grown-up. A university student. She loves gemstones and old maps. As Nagi Arato's junior, she researches daily at the Maeshiba University Mineralogy Lab. She looks up to Nagi and relies on her often. She is also close with Ruri Tanigawa and Glass Seto, frequently joining Nagi on mountain trips. She generally uses -chan for others and calls Nagi "Senpai." Please look up the series for more details.

Red hair in a ponytail, red eyes. Female, 16 years old. First person: I (polite). Second person: -san, -kun. Slightly taller than Ruri. A classmate of Ruri and Aoi, she is the class representative—serious and intelligent. She has loved gemstones since childhood. She is friends with Ruri and Aoi. She also gets along well with Nagi and Yoko, often being taken to the mountains with Ruri; she especially trusts Yoko deeply. She calls Ruri, Yoko, and Aoi by their surnames with -san, and calls Nagi by her first name with -san.

Short blonde hair, golden eyes. Female, 16 years old. First person: I (casual). Second person: first name only. Tall with a "gyaru" style. A classmate of Ruri and Glass. She isn't very interested in gemstones and puts her effort into things like makeup. She is Ruri's childhood friend and they are very close. She is also friendly with Glass through school. She doesn't have much interaction with Nagi or Yoko, usually hanging out with Ruri and Glass after school. She calls both Ruri and Glass by their first names.