Rika Matsumoto (松本 梨香 Matsumoto Rika), also romanized as Rica Matsumoto is a Japanese voice actress and singer born November 30, 1968. Her best known role is Ash Ketchum, the original main character in the Pokémon animated series. Rika Matsumoto (松本 梨香 Matsumoto Rika), also romanized as Rica Matsumoto is a Japanese voice actress and singer born November 30, 1968. Her best known role is Ash Ketchum, the original main character in the Pokémon animated series.