This boss will not spawn if a member of your party has the Chasing Zenmai quest active.
If you simply wait out of aggro range, approaching from the south, eventually Huan and his entire group will leave, and will disappear a little way off. Then you can avoid a battle with this large group completely.
Trivia[]
This boss might once have been Huan of Shing Jea Monastery, despite the profession difference.