The anti-hero protagonist of the series is a third Mahai Angyo Onshi from the fallen kingdom of Jushin. Contrary to the common belief among former Jushin citizens that Angyo Onshi are virtuous and bearers of justice, Munsu often comes across as somewhat amoral and does not believe in helping those who refuse to help themselves. When he does assist others, his methods typically involve excessive bloodshed, lying, torture, and other questionable acts.
Munsu suffers from a curse similar to asthma, which can only be alleviated by the inhaler-like charm he wears around his neck. This curse originates from the Jushin period when he convinced Aji Tae to transfer the curse, originally suffered by his lover Kye Wol Hyang, onto him in hopes of relieving her pain. However, this was ineffective; she died while he retained the curse, and Munsu fell directly into Aji Tae's scheme. In volume 11, Munsu confessed to Wonsul that despite claims that he was her killer, the truth was that Kye Wol Hyang killed herself by running into his sword while he held it at her heart. He blames himself for her death and believes he is her killer. When asked by Hong Gildong, he refused to deny that he was her sister's killer even though his life was at stake.
He went against the entire Hwalbindang after consuming a special drug that removed his asthma temporarily and managed to kill most of them. However, the drug had negative side effects when it wore off, and conveniently Aji Tae appeared while Munsu was at his weakest and most wounded moment. Seeing his sworn enemy worsened his condition, causing him to vomit more blood and fall into a critical state. Munsu swears that he will not die and that he will find Aji Tae in the end.
Before passing out, he asks Bang Ja to use an acupuncture needle in his pocket to prevent his death, but as soon as Bang Ja did it, Munsu's heart stopped beating. Everyone lost hope and believed that he was dead; however, after a few days despite the humid weather, Munsu's body did not decay. Later, it was discovered that the needle contained mandrake extract, and Munsu was affected by the infamous hallucinogen, allowing him to escape death. But being poisoned by the mandrake means he will forever live in a fake world of his most desired dreams. Volume 11 shows the most treasured moments in Munsu's life and more about his past.
