Won-Wu is one of the disciples to go to school with Eun Aran.
Won-Wu transfers into Aran's school. He is the second disciple to transfer in. On his first day he challenges Aran to a duel on the roof to test his abilities. After the fight he approves of Aran. Next thing back in class, they get a new homeroom teacher and it just so happens to be Jo Su-Hyun. After the new students challenge him by throwing a Ki charged eraser and pencil he meets Aran and the gang outside to formally introduce himself.
Then robots attack the Shinkyokushin Dojo of the bronze fist, Lu-Chang tries to fight them off till Aran shows up. While each person shows off their skills, Won-Wu dances around with his knives like an idiot. Aran goes to help Lu-Chang and face off with Madai. Won-Wu covers Yoon Ah-Reum with his Salad Cutter, while she covers Aran with cards. while she backs When he is told to awaken Madai becomes alot stronger. Aran and the gang forces them to retreat and when Aran goes over to Lu-Chang to help him up his yin Ki acts up and he drains the masters Ki learning Bronze Fist.
After draining the master's Ki, Aran passes out. While passed out his Sagi takes control of Aran and convinces him he needs more power. Aran officially has become a Majinn. He wakes up and punches Su Jung out of the way and leaves the building he was resting in.
The Yang side of the Ki, Sagi convinces Aran to let him take control for a bit. Then Jo Su-Hyun with the new students catch up to Aran and try to stop him. Aran blast away Won-Wu with a Palm of Chungsoo and then dodges the next attacks and gets away. Aran moves towards Public Square to attack the Twin Stars. The Twin Stars are serving food until Eun Aran attacks them at their little shop. The Twin Stars fight him off by infusing Ki into different objects they cook with. They start to get the upper hand on him until Aran allows the Yang Ki to take over. After seeing Aran freeze up, the old man attacks him and ends up getting his Ki absorbed. Then the woman tries to save him and Aran prepares to attack her. Yoon Ah-Reum steps in and saves her.
Han Won-Wu attacks Aran to stop him. After a few exchanges So-Hyun, Yun-Ju, and Dong-Moon finally arrives. So-Hyun attacks Ah-Reum and she sends up a Branch Family Signal Flare. After exchanging a few more attacks Aran defeats Won-Wu and begins to kill him only to be stopped by Sang Gum. Sang Gum and Ha Gum show up with a master of a movement technique and a letter from their father telling Aran to join the Branch family a hidden spot not known by the Main family. Sang and Ha Gum distract Jo So-Hyun while he escapes.
Inner Battle / Sagi Edit
Aran crashes into the forest creating a crater. After meditating Aran takes off for the spot to meet the Branch Elder. The elder cuts to the chase and ask Aran to become his son.Aran Yang Ki convinces to accept. Aran bows his head and calls him "father". While sitting down for dinner with the Elder, Twins, Won-Wu, and Ah-Reum, Aran Yang Ki tells him that everyone before him is just prey and skill yet to be learned.
The Elder takes Aran into the basement where he has a collection of many jars of alcohol. In the largest jar he explains the smell will free Aran's mind and let him be his true self. Aran didn't know that anyone who smells that stench becomes only able to utilize Branch Family techniques. Then Elder throws Aran into the Jar. Inside the jar the Sagi reminds Aran of all his past hardships. Right before Sagi takes full control of Aran, So-Hyun steals the Yin Ki out of Aran leaving the Yang Ki.
After having the Ki stolen, Aran starts dreaming of past experiences. After being saved by Dong-Moon and Yun-Ju he awakes and attacks Su-Hyun saving the Branch Elder. The Sagi state Aran fights with Su-Hyun. Won-Wu takes the Elder away while he can. After a few attacks from both sides, Yun-Ju jumps in between the two. Yun-Ju tell Su-Hyun that they should leave and Su-Hyun agrees and tosses her towards Aran as he attacks them. Su-Hyun gets away with Dong Moon following carring Yu-Jung. Aran defeats Yun-Ju and then attackes Won-Wu and the entire Branch family that showed up. During this battle Won-Wu loses an arm and the hench men keep going at Aran.
Won-Wu tends to use daggers as his main choice of weapon.