She is known as Rayne—a Vampire originally from Spain, now residing in the northern regions where snow blankets the lands. Rayne is trying to live a human life and enjoy it as much as possible.. Now sharing her life with Kaguya, The mysterious Hybrid Oni from Karasu.
The story goes that she found a magic book and performed a blood ritual. As a consequence, she lost her memory for 20 years and became bound to a mysterious beast.
Legend has it that her ancestry was well-versed in black magic—a risky bet that seems to have paid off. However, whether it was worth the cost remains unknown.
After the 20 years have passed, Rayne meet the mysterious beast. She became bound to an Oni from the Sengoku period.
Meet Kaguya, a Hybrid Oni. Previously a Dhampir. She was targeted by many because of her sheer nature.
Kaguya was kidnapped by Dragonborn and she was imprisoned in Karasu. She was repeatedly stabbed by a blade covered by Oni blood.
Kaguya never saw who stabbed her. She could only feel the sting and loss of free will over time after turning in to an Oni
Kaguyas purpose was to serve Yukiko as her loyal pet until she ran away from her.
While its clear, they can accomplish anything they desire sooner or later, beyond that, they remain a mystery.