I think, he could be the reincarnation of Dangun. BUT, he could also be the half of Jin. Just as Ja said that heavenly roots or something has two bodies for Yin and Yang. What if Jin's earthly body has been split into 2, that's why he can also contain the Black Dragon and also because he can't recall half of his memory. For the masked man, I think he may be the heavenly branch Pig God (the one with the glasses, coz why was he at the car crash? seems sus) or he could also be the other half of Jin, where the evil one and with the memory of the massacre before. Or idk I could be wrong.
I think, he could be the reincarnation of Dangun. BUT, he could also be the half of Jin. Just as Ja said that heavenly roots or something has two bodies for Yin and Yang. What if Jin's earthly body has been split into 2, that's why he can also contain the Black Dragon and also because he can't recall half of his memory. For the masked man, I think he may be the heavenly branch Pig God (the one with the glasses, coz why was he at the car crash? seems sus) or he could also be the other half of Jin, where the evil one and with the memory of the massacre before. Or idk I could be wrong.