An eternity of lightning

Astrild has been around for centuries, murdering and torturing to find the one person she's been looking for. 'The Key.' This person will be the opening to her eternity, for ever since she'd been damned to immortality, she'd had no choice but to find the person who'd given it to her in the first place; reincarnated.

She finds her key in the heart of a small girl named Crystal. Through training, her heart and mind begins to trust Astrild, and Astrild is about to destroy the soul of a modern kindergartner, but will Miles, Crystal's nuisance of a brother interfere?