Kyokutou Necromance

Kyokutou Necromance summary: One day, Kaoru Uno suddenly starts seeing mysterious monsters known as shiryo or death spirits. With the arrival of his late father's coworker Yoji Amane and a special ring his father gave him, Kaoru is ushered into the world of necromancers! From the creator of Aliens Area comes a fantastic new series of necromancer battles!