Chō'un (Shiryū) ~ Zhao Yun
Real Name: Sei

Sei is a mysterious girl who appears calm, collected, and very powerful. She is the second person to join the group. She loves to tease Aisha 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.

In Shin Koihime Musō, Sei (as Butterfly Mask), saves Tōka from bandits with her secret technique, making Tōka develop a crush on Butterfly Mask. Sei asked Tōka who saved her, and she 'innocently' said good things about her (Butterfly Mask is super cool, and noble), raising Seis mood. Sei is also scary when she's smiling (Sui has nightmares about it and Shion won't let her daughter see Seis smiling face). Sei even continues teasing Aisha in more ridiculous ways.