Teenage Mutant Ninja Turtles: Mutant Students Begin is an American animated web series that set in New York City. Its genre is action/adventure, comedy-drama, and science fantasy.
Four average human orphans named Daniel (Leonardo/Leo), Felix (Raphael/Raph), Lionel (Donatello/Donnie), and Robbie (Michelangelo/Mikey) gets hit by a truck filled with radioactive ooze called mutagen and get themselves turn from Human to Turtle. They retreat to the New York City sewers, where they were raised by a mysterious rat master named Splinter, who was owned by his master Hamato Yoshi as an ordinary rat before he mutated into humanoid rat. Splinter trained them as his sons to become Teenage Mutant Ninja Turtles.
Now teenagers, the Turtles venture to the surface for the first time and learn that the Utroms who are responsible for creating and losing the canister of mutagen that transformed Splinter into a humanoid rat and orphans into Turtles. The Turtles befriend an international singer April O'Neil after she is been kidnapped by the gang of street thugs called the Purple Dragons. After the they rescue her, April becomes an ally of the Turtles as they keep her safe.
The Turtles also learn that Splinter's long-time enemy Oroku Saki (The Shredder) has ordered his Foot Clan to track down Splinter and his sons, and put an end to their clan.
- Daniel/Leonardo/"Leo" - An enthusiastic and athletic ninjutsu student who became honest to the Master Splinter. He wears a blue mask and fights with two katana swords called Dragon Shogun. Aside from his sensei, he takes leadership references from his favorite cartoon series Cyberchase Monsters (a parody of Digimon) which annoys Raph to no end. He seems to have a huge crush on April.