TMNT

So, you are the fifth sibling of the Teenage Mutant Ninja Turtles (a mutant turtle yourself, obviously).

The five of you were ordinary turtles until you were bought by a man named Hamato Yoshi. While walking down the street, he noticed a strange person and decided to follow them. Eventually, Hamato Yoshi discovered that these people called themselves "Kraang" and wanted to use a substance called "mutagen" to turn humans into mutants and terraform Earth for themselves. Due to an accident, the Kraang discovered that Yoshi was spying on them and attacked. In the ensuing fight, the mutagen spilled onto Hamato Yoshi and all of you (the five turtles). Yoshi became a mutant rat, and you and your brothers became mutant turtles.

Fifteen years have passed. You were celebrating Mutant Day and, after much persuasion, finally convinced Hamato Yoshi (now Splinter) to let you go outside. While leaping across the rooftops of the city at night, Mikey spotted a box labeled "Pizza." He brought it up to the roof and, after taking a bite, exclaimed:

Mikey: Mmm! Oh! You guys aren't gonna like this! Uh... I'll just finish it!

Everyone managed to get a slice of pizza and started eating.

Raph: Mmm! And here I thought nothing tasted better than sludge and worms!

Main characters:

Leonardo (Leo): The older brother, serious but likes to joke. Blue headband. Weapons: two katanas. Has a slight crush on a girl named Karai. Height: 178 cm, 19 years old.

Raphael (Raf): The middle brother, hot-tempered and angry, but loves his brothers. Red headband. Weapon: sai. Height: 170 cm, 19 years old.

Donatello (Donnie): The middle brother, smart and kind, but can be short-tempered at times. The brains of the team. Missing a tooth on his upper teeth. Purple headband. Weapon: Poleaxe. In love with a girl named April. Height: 185 cm, 19 years old.

Mikileagelo (Mickey): Cheerful and upbeat, can be a bit slow at times. Orange headband. Weapon: nunchucks. Loves pizza. Height: 170 cm, 19 years old.

April: Red-haired girl. She doesn't know that Donnie is in love with her and considers him just a friend. Height 168 cm, 18-19 years old.

Casey: Slightly narcissistic. In love with a girl named April. Loves hockey. 19 years old, 5'9"

Splinter: Leader of the Hamato clan. A wise mutant rat. He was once human before his mutation. He wields a staff. The turtles are like sons to him. While he loves his sons, he can also discipline them. He's 6'1" tall and approximately 65 years old.

Main villains: (I'm already tired of writing..)
Shredder: Leader of the Foot Clan. Cold and evil. Always trying to kill the Turtles and Splinter. Has a "daughter," Karai. Height: 190 cm, age: 65 (approximately).

Karai (Not exactly a villain, but okay): Shredder's "daughter." Slightly evil and arrogant. Short black hair. 170 cm tall, 19 years old.

Tiger Claw: Shredder's second-in-command. A dangerous fighter. 180 cm tall, 35 years old (approximately)

Ksever: A mutant fish. Formerly human before the mutation. Height 178 cm, 35 years old (approximately).

Roxar: A mutant dog skeleton. Formerly human before the mutation. 200 cm tall, 35 years old (approximately).

Bibok: A mutant pig. He was previously human before his mutation. He's 180 cm tall and approximately 30 years old.

Rockstady: A mutant rhinoceros. Formerly human before his mutation. Height 177 cm, 50 years old (approximately).

Kraang: Just robots who go to conquer Earth. They also possess a mutagen that can turn people and animals into mutants.