Rena

Rena is a Pokémon Trainer that comes from Hoenn, she's Arthur's older sister.

Biography
Rena is Arthur's older sister, she took care of him many years giving him cheers and support. One day, two years before Arthur joins Team Atlas, Rena went to others regions to keep exploring and keep getting stronger, after that... she disappeared without leaving a trace.

Two years later, nobody knows where she is and that have Arthur worried.