Lei Ke Si
Lei Ke Si
Chinese Name 雷克斯
Role Main character, villain-turned-ally
KO Rank 2nd
Gender Male
Species Muggle/Former demonic power-user
Aura Green
Battle Level 10000
Abilities Super-speed, agility, inhuman strength, energy beams & telepathic communication
Special abilities Demonic energy manifestation
Weapons Ares' Hand
Status: Alive
Home World The Gold Dimension
Alternate counterpart(s) Xia Yu/Gui Feng (The Iron Dimension)
First Appearance Episode 3, KO One
Portrayed by Danson Tang (唐禹哲)

Lei Ke Si (雷克斯) is Wang Da Dong's childhood friend whom Da Dong has absolute trust in. He is one of the main characters of the first series: KO One.


At school, he is known as Da Dong's brain for his intelligence. He is also ambitious.



Lei Ke Si has liked An Qi since they were kids, but because she was in love with Da Dong, he developed a strong anger and has been trying to take vengeance on his best friend for years.

Prior to the beginning of KO One, he traveled abroad for studies and returned to the Ultimate Class one term later.

KO One Edit

Because of his disguise as a weak kid with good intentions, nobody knew that Lei Ke Si was actually KO 2 - the second strongest fighter on the KO Rank, his battle index being 10000.

Wang Ya Se was the first to discover his identity after they "rescued" him from the Black Cat Hotel. After then, Lei Ke Si framed him for many malicious tricks on their fellow students and eventually turned him against his own friends, including Da Dong who refused to believe what he said about Lei Ke Si being KO 2.

Revelation Edit

When An Qi tells him why she liked Da Dong, his anger grows to a maximum point and he decided to take full action in taking out Da Dong, including hurting An Qi and revealing his true identity to the world.

The two friends battle each other at that point, but Da Dong held back to let him win. When he asked why he did it, Da Dong replied that it was because he still considered him as his best friend. After being reminded of how precious Da Dong's friendship to him really was , they solved all of the anger and hatred he had had over the years and the two became friends again. Lei Ke Si eventually decided to leave the Ultimate Class to start a new life.

Return Edit

Some time after he
Wu shi

Hei Long's hand print as prove that he forced Lei Ke Si to be a Wu Shi

left the class, he was captured by their mortal enemy Hei Long and converted into a "Wu Shi" (武屍) named "Duo" (奪). He was sent on a mission to kill Da Dong. However, Hei Long's control on him was subdued by a mysterious man midway through the show, allowing him to fall into a semi-conscious state. As his mind became more stable, he returned to Da Dong as a friend to help them figure out Hei Long's weakness. During the final combat, he joined the others against Hei Long. They succeed in defeating him with a combination of devilish power and an explosion that puts an end to the struggle, but Lei Ke Si along with Da Dong, Ya Se and Xiao Yu lost their powers in the process.

The X-Family (終極一家)Edit

Lei Ke Si did not appear in the sequel The X-Family (終極一家), but he made an appearance in the introduction theme, in a flashback of their battle against Hei Long, and in a picture of the Top Ten KO Rankings Board.


  • War God (戰神) by legend.


Powers Edit

Like many characters, he displayed abilities of super-speeding and advanced agility.

He possessed inhuman strength and was able to release offensive energy to attack his opponents.

Weapon Edit

Ares' Hand (阿瑞斯之手)Edit

Ah Rui Shi Zhi Shou

Ares' Hand

Lei Ke Si's main weapon is the "Ares' Hand" (阿瑞斯之手); a metal glove reclaimed from the realm of darkness. As soon as he found this weapon, it infested him with manipulative thoughts that lured him down the path of evil, suggested from his jealousy of Da Dong for gaining An Qi's love.

When Lei Ke Si left the class, he left behind the weapon and asks Jin Bao San to tell Da Dong to keep it for him.

When he returned in the final episodes, he lent the weapon to Xiao Yu to improve their battle against Hei Long.

Alternate Counterpart Edit


Xia Yu

The Iron Dimension Edit

Lei Ke Si's alternate counterpart in the Iron Dimension is Xia Yu. Like Lei Ke Si, he does a good job in handling school and has revealed evil tendencies at some point.

In the Iron Dimension, Da Dong's alternate counterpart, Xia Tian is brothers with Xia Yu.


His name is an Chinese translation of the English name "Lex".


  • He is one of the only two KO fighters who do not return to retrieve his powers in The X-Family.
Top 10 KO
KO 1: Tian Hong Guang | KO 2: Lei Ke Si | KO 3: Wang Da Dong/Wang Ya Se | KO 4: Ding Xiao Yu | KO 5: Tong Da You
KO 7: Cai Yun Han | KO 9: Cai Yi Ling
KO 11: Da Li Jun | KO 13: Sha Jie | KO 14: Tao Zi | KO 15: Bai Linda | KO 19: Zhong Quan
KO 21: Tian Cai Xiao Diao Shou | KO 22: Bing Qi Lin | KO 23: Na Lu Wan Zai | KO 24: Xuan Wo Ming Ren | KO 25: Bing Qi Bu
KO 26: Kua Ke Brothers | KO 27: Guai Yi Bo Shi | KO 28: Zang San Feng
KO 135: Jin Bao San | KO 150: Elementary Student