Yeouiju (or Yeo for short) is the ancient dragon spirit that guides and protects Kim Wu in Killer Instinct (2013). He is a minor character of the Killer Instinct lore who was first introduced in the 3rd chapter of the Killer Instinct Novella, titled "Dragon's Choice".
Yeouiju is among the mightiest of astral spirits that once dwelled in the same Astral Plane where Gargos now holds dominion. Finding his refuge on Earth, he has acted as a guardian to Kim Wu's Korean family for more than two thousand years. At first residing within Kim Wu's uncle, Philip Yong, Yeouiju was transferred to Kim at the moment of her uncle's death. Yeo soon after revealed himself to her in a vision, in which he took the guise of a modest and dignified Korean man with cat-like golden eyes, before appearing to her in his dragon form. Upon bonding with the fiery young martial artist, Yeouiju emblazoned a beautiful tattoo all the way down Kim Wu's right arm, marking her as the dragon's chosen one in the coming war with Gargos.
Yeouiju resembles a small, translucent Chinese dragon with two antlers, and no visible arms or legs. He is golden in color, and is bathed in an azure aura which alternates between a heavenly bright and a more subtle hue. Yeo can manifest as up to three different projections of himself, and visibly floats around Kim Wu when she has Dragon Charges available in combat. He himself acts as a powerful projectile when Kim uses her Dragon Cannon ability.
In the Killer Instinct Novella, Yeouiju's human appearance is described as "a lithe and muscular Korean man of indeterminate age, dressed in silk robes", who has "a long salt and pepper colored mustache and goatee" and "eyes like molten gold orbs with a cat's vertical pupils", and who displays "the dignified yet modest bearing of a Kung Fu master."
—Yeouiju's first words to Kim Wu, spoken in Korean
—Yeouiju's words as he enters into Kim Wu's heart, bonding with her
—Yeo telling Kim of Hisako's tragic legend during Shadow Lords
- The Novella's description of Yeouiju's human form closely matches the appearance of the unnamed "dojo master" seen in Killer Instinct Gold 's training mode, who is located within Kim Wu's stage.
- Yeouiju shares many characteristics with the Tianlong, the heavenly or holy dragons from Chinese mythology.
- In Korean mythology, the "Yeouiju" are mystical orbs that certain Korean dragons are depicted as holding in their claws. It was said that dragons who wielded the Yeouiju were blessed with omnipotence and had the ability to create at will.
- "Yeouiju" is the Korean word for "Cintamani", one of the wish-fulfilling jewels mentioned in Buddhist scripture.