|“||We should have dumped a bucket of water on Gilhong's head while he was asleep.||”|
Hajoon is a senior student of the Hongmoon School of martial arts. He has a carefree attitude, but genuinely cares for his fellow Hongmoon brothers and sisters. He is an expert in the martial arts and is capable enough of teaching others.
Hajoon was fast asleep when the newest pupil, nicknamed Cricket, came in to wake up his roommate Gilhong. He wakes up to meet Cricket and tells him/her that they should have dropped water on Gilhong's head instead of shaking him awake. Cricket then leaves with Jinyung and Hajoon goes to meet up with Master Hong Sokgyun with Gilhong.
After Master Hong dismisses them, Hajoon goes to continue his training along with the others. When Yungmuk announces that Cricket has been accepted into the school, Hajoon congratulates him/her for making it in. He goes back to his training while Yungmuk teaches the new pupil the basics.
When night fell, Hajoon went to the Proving Grounds and encountered shadowy fiends. He fights them off with Lusung and tells Cricket to go find the others. During the battle, Hajoon is struck hard and falls off of Heaven's Reach into the sea below.
Believing himself to be the last surviving member of the Hongmoon line, Hajoon makes his way to Bamboo Village and eventually Jadestone Village. During his journey, he hears word of another Hongmoon survivor and sends a message to the pretender to meet him in the Abandoned Well in Everdusk. Upon encountering the so-called pretender, Hajoon immediately recognized the person as Cricket and engages the person in combat to test his/her skills. He is impressed and reveals himself to Cricket, who becomes overjoyed to see him alive.
For the next several days, Hajoon teaches Cricket all he knew about the martial arts while encouraging him/her to team up with others to unleash more powerful attacks. As time went on, Hajoon steadily became more and more sickly and he eventually reveals to Cricket that he has been afflicted by the curse of the Mark of the Black Rose. He goes on to say that anyone affected by the curse is doomed to a slow and painful death. Despite that, he continues training Cricket until he eventually dies in the Gloomdross Forest.