Amane Bakura is Ryo Bakura's deceased younger sister. She is mentioned in the Yu-Gi-Oh! manga when Ryo is seen writing a letter to her.
Amane died in a car accident at a young age along with her mother. Her brother, Ryo, wrote letters to her in Heaven. Before his dark other self appeared, Ryo was writing the following to Amane:
How is school? How are you and mother? Your brother started his new school today. I've only been there a little while and on the very first day I made a lot of new friends. They asked if they could come over to my apartment to play some games. I'm really looking forward
He then stopped as he heard Dark Bakura chuckling malevolently.