Sensei Kanoi Watanabe

Sensei Kanoi Watanabe is a character on Power Rangers: Ninja Storm. He is introduced as the mentor of the Wind Rangers and father to Cam Watanabe. He is changed into a guinea pig in the first episode by his evil brother, Lothor. Later, he becomes a mentor to the Thunder Rangers after they join the team.

Biography
Kanoi was originally an air ninja, and, with his twin brother, Kiya, joined the Wind Ninja Academy sometime during the mid-1980's. While a student, he met Miko. When Cameron Watanabe went back in time to retrieve the Samurai amulet, Kanoi, not realizing Cameron was his son from the future, distrusted the stranger and, when the amulet went missing, accused Cameron of stealing it. Kanoi was later instrumental in revealing that Kiya had actually stolen the amulet and, as a result of his actions, Kiya was expelled from the Wind Ninja Academy and disowned by Kanoi. Kiya changed his name to Lothor and vowed to return to Earth to seek revenge against Kanoi.

After Kiya's departure, Kanoi and Miko were married. Together, they had one son, Cameron. At some point early in Cameron's life, Miko died. She made Kanoi promise her that he would not train Cameron in the martial arts, a promise to which Kanoi reluctantly assented.

Ninja Storm
Lothor returned to Earth in 2003 and quickly defeated most of the ninjas at both the Wind and Thunder Ninja Academies. Lothor used his magic to turn Kanoi into a guinea pig, albeit with the ability to speak and bipedal movement. Three of Kanoi's students, however, were absent during the attack and, sensing potential in them, Kanoi makes Shane, Tori, and Dustin the Wind Rangers. It is later revealed that he knew the Scroll of Destiny had foretold that they become Power Rangers.

He also sensed potential in his son Cameron, but had promised his wife that he would not train Cam in the ways of the Ninja. So, instead, Cam learned to become a samurai, and met his father in the past before obtaining the Samurai Cyclone Morpher.

In a later episode, Cam created a machine that should have returned his father to a human, but instead he swapped bodies with both Shane and Dustin, before finally returning to his trapped hamster body. It reveals he's proficient in Earth Style, despite beginning his ninja training as an Air Style Ninja.

Kanoi was eventually restored to human form, and returned to the Wind Academy.

Dino Thunder
He was later captured and impersonated by a vengeful Lothor, who tricked the Wind Rangers and turned them into his servants. Kanoi later escaped with the help of his nieces Marah and Kapri, and helped Cam and the Thunder Rangers recover their powers from the Abyss of Evil. He then worked together with Hayley to advise the Rangers in their team-up battle.

Trivia

 * Sensei and another character of Ninja Storm, Eric McKnight, have twin brothers that appear in Dino Thunder.
 * According to the episode The Wild Wipeout, Lothor is a Libra. This makes Sensei a Libra as well, since they are identical twins.
 * Chuubo thought that Sensei was a hamster. This is a reference of Sensei's sentai counterpart transforming into a hamster.