Yamiyoryu

Yamiyoryu is a demon that is currently sealed inside Amaya Mizuno.

Background
Several years ago, Yamiyoryu would often terrorize villages in the middle of the night, killing many. However, members of the Mizuno Clan managed to seal the creature away. At first it was sealed within objects such as scrolls or containers. Over time it became apparent that a stronger place to seal the creature was needed. The members of the clan then decided to begin sealing the beast within one of the clan's current heiresses in order to better keep the creature at bay and prevent it from terrorizing villages once more.

For many decades now, Yamiyoryu has been sealed within heiresses to the Mizuno Clan. Overtime, many forgot about the beast's existence and has become a closely guarded secret of the clan.

Abilities
Due to not being a tailed beast, Yamiyoryu has very small reserves of chakra in comparison. However, her abilities rely heavily upon her ability to slip into the minds of others. By doing this she is able to gain some control of others and can make those under her control do tasks for her bidding. However, that ability has its limitations, as she is unable to make a target kill themselves or perform tasks their bodies initially cannot already do. Additionally, she is able to control what someone dreams, to an extent.

Additionally, due to her status as a dragon, Yamiyoryu is able to utilize fire. However, her abilities are limited to exhaling large bursts of flames.

Trivia

 * Due to many not initially knowing of its existence, many assumed that Yamiyoryu must be a tailed beast like Kurama. However, Yamiyoryu is not a tailed beast but a demon that terrorized villages many years ago.