Arist Craisi

One day Elise dug up Gran, a young man who was buried alive by the villagers. Since Gran is missing a heart, people called him the "nameless monster". Elise then said to him "Maybe you are the one that I've been looking for." Elise herself is a "Arist Craisi" also known as a cavity demon. Her sole purpose to life is to hunt down other "Arist Craisi" and complete her revenge. A tale of battles between monsters, the beginning of the illusory yet melancholy dark fantasy!

(Source: Famitsu Bunko, translated)