full ref sheet of my sona in the second and last step of his warrior transformation, the seal on his back is entirely disappeared and he is not himself anymore, he is possessed by a bad spirit, someone must stop him and tries to reform the seal on his back, he can't regain consciousness by himself.

The different forms:

Basilic: https://www.weasyl.com/character/8429

Shinigami no Basilic: https://www.weasyl.com/character/8437

Kenzan: here