Ido Front

Ido Front (fan translation: Idofront), also known as the Forward Operating Base, is a research station located at the bottom of the 5th layer. It is the deepest a person can go and still survive the curse. It is the place where White Whistle Delvers begin their Last Dive.

Its main purpose is as a gateway into the 6th layer. Its center, the Altar of the Absolute Boundary, acts as an elevator through the Sea of Corpses, and it can only be activated by the sound of a White Whistle.

History
Long ago, Ido Front was originally the ruins of a former ritual site where preparations were made and the ritual was held. It has been transformed into Bondrewd's main base of operations since approximately 10 years ago. Here, he conducted experiments resulting in technology to combat the curse, albeit at a cost.

Nanachi, Mitty and other children were brought to Ido Front to fulfill roles as his test subjects. It is also here where Nanachi and Mitty were transformed into Narehate after ascending from the Miniature Garden of Dawn.

Prushka, Bondrewd's adopted daughter, was raised here before being turned into a Cartridge and subsequently a Life Reverberating Stone.

Trivia

 * The cylindrical structure above the Ido Front is a pillar of frost.
 * Based on a comment from Majikaja stating that Nanachi is a Narehate of the "old ritual site," it is possible that the rituals that took place at Ido Front long ago involved an individual receiving the blessing. How the blessing was achieved by the ancient people is unknown.
 * The crystals formed at this self-regenerating ritual site, which are seen during Ganja's travel on the path leading to the Altar of the Absolute Boundary, are said to be the accretion of excess residue during the healing process. Yet in Riko's day and age, the place has been neatly cleaned up.