full ref sheet of my sona in the first step of his warrior transformation, the seal on his back half disappeared but he is still himself, you don't have to worry, in this form, he can return back easily into his initial form :3
The different forms:
Basilic: https://www.weasyl.com/character/8429
Shinigami no Basilic: here
Kenzan: https://www.weasyl.com/character/8438