Master Lee playing an important role here- 

Updated until episode - 11

• Transfers the remains of soul finder magic dog GwilJu to real dog body

• Allows Uk & Mudoek live at his small place in DanHyanggeok 

• Finds out Mudoek has a different soul in her body, and it might be Naksu.

• Watches Uk being taught Tansu by Mudoek and helps them keep the secret

• Gets close to Park Jin finds out about Icestone, UK's birth history, JinMu's goals and Jinyowon. 

• Helps Uk at Songrim at the right moments

• Gets close to Kim DoJu without Park Jin knowing 

Master Lee is indeed amazing character who keeps secrets. He knows story of icestone where it might be and what it can cause. He knows soul shifter Naksu is UK's master. He doesn't tell Park Jin about Uk-Mudeok story. He doesn't tell Uk or Mudoek about the King's star or soul shifting or anything! 

Very very interesting!