Two-Headed Black Dog

Summary
The Two-Headed Black Dog is an animal-like monster that strongly resembles a dog from Naofumi world. Similar to the Cerberus but instead of wielding three heads, it only wields two.

The Two-Head Black Dog is one of the monsters that appear out of the several rifts in the sky during the First Wave and attacked Raphtalia's Village. After the destruction of the village, the Two-Headed Black Dog along with several other monsters from the wave inhabited the old coal mines near Riyute Village.

Because the coal mines were full of monster, the villagers in Riyute abandoned the coal mines. The Two-Headed Black Dog was later killed by Naofumi and Raphtalia.

Debut
Anime: Season 1, Episode 2

Manga: Volume 1, Chapter 4

Light Novel: Volume 1, Chapter 16

Web Novel: Never Shown

Trivia

 * The Two-Headed Black Dog reminds Raphatalia of the Cerberus that killed her parents.
 * Raphtalia overcame her past trauma after killing the Two-Headed Black Dog