Anime version
Choun is a mysterious girl who appears calm, collected, and very powerful. She is the second person to join the group. She loves to tease Kan'u and other women frequently. She also assumes the identity of a hero of justice named Butterfly Mask, hence wearing a Butterfly mask.
In Shin Koihime Musou, Cho'un (in Kachou Kamen's form), saves Ryubi from bandits with her secret technique, making Ryubi develop a crush on Kachou Kamen. Choun asked Ryubi who saved her, and she 'innocently' said good things about her (Kachou Kamen is super cool, and noble), raising Choun's mood high. Choun is also scary when she's smiling (Sui will have nightmares about it and Shion won't let her daughter sees Choun's smiling face). Choun even continues teasing Kan'u in more ridiculous ways (like an embarrassing introduction of Kan'u to the bandits who attacked Ryubi - and Choun gets a lump on the head as a result).
In Koihime Musou's OVA, Cho'un (as Kachou Kamen) appeared and swam, but Kouchuu, who acted as the school's doctor, said that its okay, since Kachou kamen's appearance looks like Cho'un, and she immediately tied up and put into an unused class, until night and no one seems to notice her missing (even her daughter, who asked about her whereabouts before).
Visual novel version
When Kan'u was fighting the To army, she fought alongside Cho'un for a while; when this war ended, Cho'un met Kazuto and took a liking to him, promising to join his army later. She joins alongside Kochu after the battle with Ensho. She has a strong obsession of menma. She also has a habit of running around the city as the masked hero of justice 'Butterfly Mask'. Strangely, no one other than Kazuto and Shuri can recognize her true identity, despite only wearing a mask.
(wikipedia.org)
Vova
