Izoku

The Izoku are a race of monsters native to the world beneath the Earth's surface, Agartha. Although the Izoku are hostile, they actually form the balance within Agartha.

History
The Izoku debut when they first approach Asuna in her sleep, after she and Mr. Morisaki arrived in Agartha. The Izoku brings Asuna to an ancient ruin where she wakes up and finds a young native girl of Agartha named Mana, who was also kidnapped by the Izoku. As Asuna tries to find a way out, Mana points out the Izoku appearing from a darkened area. As the Izoku corners Asuna and the Agartha native, Asuna discovers the Izoku are susceptible to light as the sun is shining above them. As Asuna and Mana try to reach for the exit above as the darkness closes in but are unable to, Shin, another native who Asuna met in her world, rescues them after he sensed her with his crystal. They then flee as the ruins continue to darken, allowing the Izoku to give chase. Once the Izoku corners the trio by a cliff, the three of them jump into the river below with two of the Izoku still on their trail. Asuna and Shin believe they are safe, but then one of the two Izoku stabs Shin