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Kai and Nya's Father is a minor character in LEGO Ninjago: Masters of Spinjitzu. He was the best friend of Sensei Wu, and the father of Kai and Nya by an unknown wife.

History
In his youth, Kai and Nya's father fought alongside Sensei Wu and Lord Garmadon in many battles, including the Serpentine War. Like his son, Kai, he was headstrong and reckless, but a skilled fighter and a loyal ally.

One night, he and Sensei Wu were searching for samurai bandits, but when he spotted the silhouettes of scarecrows, he mistook them for the bandits and sprung into battle. The next morning, he was forced to apologize to the farmers that owned the scarecrows for his mistake.

Kai and Nya's father eventually became one of Sensei Wu's most trusted friends. As such, the old master entrusted him with the map to the Golden Weapons, made in the event of Wu's demise to ensure that the powerful artifacts could be retrieved in times of darkness.

Later, Sensei Wu wanted him to become a ninja, though he declined to stay at home with his wife to take care of their children and work at Four Weapons Blacksmith. When he passed away, Kai and Nya became the new owners of his blacksmith shop.

Spinjitzu Smash DX
Kai's father also appeared in the online game Spinjitzu Smash DX. He made his appearance in fifth level, being titled just Kai's father. He appeared as a ghost, calling Kai's name.