The Hamato Clan was once led by the mutant rat patriarch Hamato Splinter, who raised four adopted mutant turtle sons Leonardo Hamato, Raphael Hamato, Michelangelo Hamato and Donatello Hamato. They met and befriended April O'Neil, who took them in after their first sewer lair under Manhattan was destroyed. Raph independently befriended Casey Jones, while Mikey found and adopted Klunk as his pet cat. April was eventually regarded as part of the family, acting as a big sister to the four turtle brothers and a daughter figure to Splinter.