Izanami

Goddess of Death, an enigmatic figure that guards the pathways connecting "deathspace" and the Sea of Souls and commands the concept of death itself, taking people's souls when their time is due.

She's known to have the power to kill universes if she wants to, and almost did so once.

Story
She dragged Ienzo Excellion and Tael (and maybe other older characters that I forgot) into an incident several thousand years ago, baited by Excellion of course. Nothing else was shown of her yet.