Kai Green

Kai Green is Ben's first love interest, who makes her appearance in Benwolf. Kai is the granddaughter of Wes Green, a friend and former partner of Grandpa Max. She first appeared doing a spiritual dance in the episode Benwolf. She was Ben's first crush, but she only took interest in him after he started becoming Benwolf because she wanted to, as quoted, "train and tame him". She did have an interest in him before he turned into Benwolf but the interest was about the Omnitrix. When she admitted to this, Gwen gave her a stern talking too. She made a cameo appearance in Ben's dream world in Perfect Day (though it was only a dream).

Ben 10

 * Benwolf
 * Perfect Day (dream)

Languages

 * In Hawaiian "Kai" means "Ocean" or "Sea".
 * In Maori "Kai" means "Food".
 * In Portuguese "Kai" is pronounced like the word "cai" which means "Falls".
 * In Romanian "Kai" looks like the word "cai" which means "Horses".
 * In Japanese "Kai" means "King" it can also mean "Sea" or "Ocean".
 * in Lithuanian "Kai" means "When".

Trivia

 * In Ken 10 it is seen that Ken Tennyson's skin color is a mix of white and native American.﻿ According to the pop-up version in an alternate timeline Ben would eventually marry Kai, and she is Ken's mother.
 * According to Derrick J. Wyatt, Ben is going to marry Kai in Omniverse.