Sanagi no Heart

The Chrysalis Heart; サナギの心臓; Sanagi no Shinzou; Trái tim của nhộng

Welcome to the Demon Realm, where Meitaro, a young demon lacking magical powers, seeks to gain strength by consuming a human heart.
But when he summons his prey, he finds only a frail young girl.
As their fates intertwine, their relationship takes an unexpected turn...
Akari Kajimoto presents a dark tale of twisted love.

(Source: MangaPlus)