|Ruler of||Onii Kingdom|
|Captured Princess||Princess Apricot|
- "What's mine is mine, what's yours is mine."
- — Onii King
The Onii King is smugly lazy and indolent. He hates Corobo, trash-talking him for invading his land. After losing, he is shown to be a coward as he runs away and forfeits his land.
After the Onii Grounds are taken by Corobo, the Onii King sends a Letter of Challenge to Corobo. He refers to Alpoko as Aljerko, calling Corobo a jerk and claiming himself to be the best.
The Onii King leaves taunting messages to Corobo on signs throughout Dark Valley, some of which are guarded by Onii.
When Corobo confronts the Onii King at the end of the Dark Valley, he claims that all the land Corobo has taken is rightfully his. He brings a frozen hoard of Onii to life with his breath, who take their positions and begin to fight Corobo.
After his defeat, he runs off his throne, and submits the Dark Valley to Corobo, never seen again for the rest of the story. After the Dark Valley is taken by Alpoko, the Onii flee to other Kingdoms, and Princess Apricot is freed from the vase the Onii King trapped her in for 100 years.
The Onii King stays put on his throne for this fight, only counterattacking and throwing projectiles across the battlefield. Despite being the first King battle, the mechanics behind the fight are fairly complex.
The battlefield has the Onii King sat at the north-centre, with two cliffs on either side of him. Atop these two cliffs, Onii will be carrying pots and rocks. If they reach the Onii King and he is not currently attacking, the Onii will throw the projectile to the Onii King, who will then perform one of two throw attacks. If the King is currently busy throwing another projectile or kicking, the Onii will throw the rock or pot directly at Corobo and his Royal Guard. If the Onii are attacked by Animal Hunters, the projectiles can be shot down and broken prematurely.
The Onii King has two counterattacks, depending on where he is being attacked from. If any non-Soldier citizen attacks the Onii King first, they will attack his feet, and the Onii King will kick them in return. If a Soldier attacks the Onii King first, they will cling to and attack his chest, then he will shake his body to remove them. However, if this latter counterattack if performed while a rock or pot is being passed to the Onii King by an Onii, it will hit his head instead, causing him to be stunned for some time. After his stun is over, he will perform an eruption attack with wind properties, damaging anyone close to him and pushing back anyone in the middle of the arena.
In front of the Onii King are three breakable logs, blocking the way for citizens to reach Onii King without Corobo getting too close. To the Onii King's left, or the player's right, is another Onii throwing rocks and pots from behind a line of breakable logs. If this Onii is defeated, x10 Arrows will be awarded to Corobo.
At the very back of the arena is a Hot Spring, and swarms of pots that may be broken to regain more Arrows.
|Pot throw||Projectile||Once an Onii reaches the Onii King they will pass him a pot to throw|
|Pot launch||Projectile||Same as Pot throw but with extra start-up and a faster travel time - tends to be used when Corobo is further away|
|Kick||Counterattack||Used when attack comes from a non-Soldier citizen attacking Onii King's feet, quick start-up, hits around feet|
|Shake||Counterattack||Used when attack comes from a Soldier, almost immediate start-up, hits around entire body - will stun Onii King if used as a pot or rock is being passed to him by an Onii|
|Eruption||Area-of-effect||Performed after stun has worn off, covers a wide area around Onii King and grants him invulnerability during the attack, wind pushes Corobo and his Royal Guard backwards if they are in the middle of the battlefield|
New Little King's Story
The Onii King returns in New Little King's Story, fulfilling an almost identical role and boss fight. His personality is changed to make him more unintelligent, similar to his letter to Corobo in the first game, but inconsistent with his actual speech from the first game. He also seems to believe that Apricot is his girlfriend, something she is not aware of.
- The UMA Book has an unused entry for the Onii King, suggesting he was once planned to be a Guardian.
- According to the NTSC game pamphlet, the Onii King and King Duvroc are friends.
- The inspiration behind the Onii King is never made clear in-game or by any developers. However, the Onii species are based on demons from Japanese mythology.
- The Onii King is the only Onii with three horns, shaped like a crown.