Miyumi

Miyumi is a friend of Daphne Blake and associate of Mystery Inc.. She was also, initially, a traitor to her friend because her true loyalty was to Miss Mirimoto.

Scooby-Doo! And The Samurai Sword
Miyumi didn't know the whole plan, but she was instructed to get close to Daphne. Once she knew the intention was to revive the Black Samurai she turned on her teacher and helped the gang. In the end they offered her a place on the team, but she turned them down in order to find what she did best.

Appearances

 * Scooby-Doo! And The Samurai Sword