Katrielle "Kat" Layton is the protagonist of Layton's Mystery Journey: Katrielle and the Millionaires' Conspiracy and its anime adaptation, and the adopted daughter of Professor Hershel Layton. A "riddle-solving detective" and founder of the Layton Detective Agency, Kat takes on various cases brought to her by fellow Londoners in the hope of finding her missing father. She is assisted in her investigations by her devoted assistant Ernest Greeves and a talking dog named Sherl.