|Nickname|| Element of Danger|
Sun-Woo Clan Head
Most Dangerous Man
|Relatives|| Mrs Yi (mother)|
Mr Yi (Father-unknown)
|Affiliation|| Nine Dragons High School|
Martial Arts Alliance
|Occupation|| Sun-Woo Clan Ganju|
Martial Arts Alliance Danju
|Operates in|| Murim|
|Master|| Chun-Woo Han (Former) |
Jang-Il Jeong (Former)
|Style|| Black Heaven & Earth|
|Part 1||Chapter 1|
|Part 2||Chapter 1|
Shi-Woon Yi is the main protagonist of The Breaker Series. He is the first official disciple of Chun-Woo Han, the Goomoonryong, and the current Head of the Sun-Woo Clan, and the Danju of the Martial Arts Alliance.
Shi-Woon looks much like any other Korean high school student, often dressing in his uniform and later on in sweat suits. He has shaggy hair and an unremarkable "failing" face. His body is particularly skinny with little to no muscle at the beginning of the series, as made evident by his inability to complete most basic physical exercises, which may be due to his particular body condition, resulting in a body that was naturally inferior since birth.
Although his strength has increased after training with Goomoonryong, his body does not seem to have changed much; however, his fashion sense looks to be getting more and more like that of So-Chun Hyuk. Recently his body has looked more muscular but nothing comparable to other Murim like Chun-Woo Han or Ha-Ill Gang.
After the S.U.C.'s invasion in the Nine Dragons High School, Shi-Woon underwent the phenomenon called Overhaul Rebirth, which is said to rearrange the body. However, no distinct outer change has been visible aside from So-Chun Hyuk commenting about an increase in height. This comment may be more focused on Shi-Woon's increased mental, spiritual, and social presence instead of on his literal height.
Prior to meeting Chun-Woo Han, Shi-Woon was a coward and was a constant target for bullies. No matter how far Chang-ho and his gang went, Shi-Woon was too cowardly to oppose them. This led to him being treated as a kind of slave at times.
He was unable to properly talk with his crush, Sae-Hee. Even though she was supportive and kind, consoling Shi-Woon when she saw him after a beating, Shi-Woon was unable to handle the attention and broke down sobbing at how helpless he was in front of her. His feelings were so fragile and confused that he even yelled at Sae-Hee. Eventually, all of this stress added up, and Shi-Woon lost hope in life. He was convinced that dying would be better than the life he was living and prepared to kill himself. This all changed when Chun-Woo Han arrived at school.
By learning from Chun-Woo Han Shi-Woon was able to slowly develop his own will and courage based of his own spirit and Chun-Woo's blunt lessons. Unlike Chun-Woo, Shi-Woon has shown an utter distaste for killing, talking his master out of killing enemies despite the consequences. Shi-Woon has no problem with depending on others but also has an overwhelming resolve to protect those he cares for. This trait was present before training, but afterwards, he has the ability to act on it more effectively. He is still very meek and prefers to avoid confrontation unless the situation calls for it.
According to So-Chun Hyuk, Shi-Woon is a person who surpasses the instincts of mankind. This means that he is prepared to die whenever he fights, abandoning the fear that most people have while fighting. This lack of fear then has the reverse effect on his opponents, making enemies who are even superior to Shi-Woon fear him.  Ju Sang-Sik has also mentioned the same thing, stating that Shi-Woon fights like a veteran of the Murim. He also states that contrary to his innocent nature, Shi-Woon is very calculating.
It should be noted that throughout the series his resolve (guts/Spirit) not only irritates others but can even leave people to pondering his magnificence. This effect is so powerful that many people have gone from disliking, or even wanting to kill, Shi-Woon to actually joining his cause or falling for him. This "skill" has been effective on everyone from peers and schoolgirls all the way to elders, geniuses, and even homicidal masters. Some examples: Chun-Woo Han, Shi-Ho Lee, Jang So-Sul, So-Chun Hyuk, Jin-Ie Kwon, Ji-Gun Yoo, Sera Kang, Elder Jeong, Elder Kwon, Mun-Gi Ma.
Another trait he seems to have picked up from Chun-Woo is having small bouts of uncharacteristically strong rage. These have been seen when something he cares for has been insulted, threatened, or hurt. This is seen when Chang-Ho threatens Sae-Hee in the first part of the series but is not as intense until later one. His rage again appears when he finds out that the S.U.C. had severely hurt his mother and when he learns that Sera Kang was hurt using while herself as a distraction. This rage leads to him entering the Black Origin Threshold when Jang-II Jeong is seemingly killed by an explosive during the S.U.C.'s attack on his school. More recently, he has developed a great pride in the Sun-Woo clan. If anyone insults or debases the Clan, even indirectly through not respecting him as the Ganju, Shi-Woon reacts with rage and anger. Having had drastically different experiences within the Murim, master and pupil also differ in temperament when their rage does manifest. Chun-Woo will often show sadistic pleasure along with his rage while Shi-Woon simply becomes cold, determined and assertive.
Shi-Woon is also able to hide his Ki much more effectively than people who are above master level. This ability allows him to move around unnoticed and to hide from even experienced martial-artists as is demonstrated in the events following the S.U.C.'s attack on his school. Only grandmasters so far have been shown to detect his presence.
After being given the seat of the Martial Arts Alliance Chief, Shi-Woon desire to become stronger was strengthened as he needed to be stronger in order to live up to the responsibility and trust placed on him. He also developed a desire to fight in order to see how much he improved. This was seen when he was leaving the the MAA building and came across So-Chun Hyuk, upon seeing him he was thinking about fighting him to see how much he improved.
- "If it weren't for Sunsengnim . . . I probably wouldn't be here today." - Shi-Woon to Chun-Woo
- "Both disciple and master are absolute morons." - Takeshi in reference to Chun-Woo and Shi-Woon
- "My fist isn't that weak! You think I'd lose to those pseudo-martial arts?!" - Shi-Woon to Yong-Hyun Yan
- "I don't know what happened, but I'm glad to see him in the Murim again." - Kang-Sung in reference to Shi-Woon
- He is the driving force of the story in New Waves.
- Shi-Woon was dubbed by So-Chun Hyuk as the first person to defeat him.
- He has experienced a similar incident in both Part I and New Waves at around the same chapter time. In Part 1, he faced off against So-Chun Hyuk and in New Waves with Ji-Gun Yoo. Both individuals were prodigies, beat him brutally in battle, were affected by his spirit, and both accepted defeat after being hit only once. Also, in both manwha's, Shi-Woon gets pursued by a large group of people and these events both begin after something huge happens to Shi-Woon. In The Breaker, he finally masters a foot technique and the Soul-Crushing Strike. In New Waves, he goes though Overhaul Rebirth.
- Both he and his master have had their arms in a sling for a time and engaged in battle regardless.
- Both he and his master have a fierce side with both promising to crush a certain group of people. Chun-Woo Han the Martial Arts Alliance and Shi-Woon Yi the Soldiers Under Command.
- Shi-Woon Yi's name means "lucky stone" in Korean language.