Choun Shiryu is a fictional character from Koihime Muso. 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, and seems to relish whenever she gets up close with them. She also assumes the identity of a hero of justice named Butterfly Mask, hence wearing a Butterfly mask. This character is popular among cosplayers. It can be portrayed by wearing cosplay Choun Shiryu costume and cosplay Choun Shiryu wig. This character is always present in a Koihime Muso cosplay.