Hiruko

Hiruko (ヒルコ) are horrific creatures, making a frequent appearance as a threat in the Heavenly Delusion series. They are often referred to as a ''Man-Eaters' (人食い/), and are called beasts many times throughout the series.

The name by which they are called differs depending on the person, or the area. The existence of Hiruko are the result of Takahara Academy's children dying after having been afflicted by an autoimmune disease; causing them to mutate into monsterized versions that are hostile to all life. Each Hiruko mimics and/or approximates the abilities of the person they once were.

Their food primarily consists of human themselves, in which poses a great threat to humans who survived the disaster years ago.

Physiology
All Hirukos are immortal. While it appears throughout the series that Hiruko's may appear dead, they can only sustain physical damage and be put in a near death state. Maru however, has a unique ability which can put an end to a Hiruko effectively; an ability none except him, currently has.