yoshi raises the turtles by himself and gives them the names of his favorite renaissance artists: leonardo, donatello, raphael, and michelangelo. yoshi is given the nickname "splinter", due to his proficiency at breaking wooden boards, and he teaches them the art of ninjutsu in order to protect themselves. like many real-life ninja masters, he has a strong sense of honor and follows very strict rules which all four of his students adopt.