Bondrewd

ボンドルド

Bondrewd is a legendary white whistle delver who has made many significant discoveries regarding the secrets of the Abyss. Fascinated by the Abyss as a researcher, he has frequently resorted to illegal and morally questionable methods to secure funding and conduct his studies, including the illicit sale of artifacts, the development of dangerous drugs, and even experimentation on living humans. Despite his cruelty, he still cared for the children and people he brutally experimented on.
His methods violated all ethical principles of delvers, yet he was permitted to continue due to his outstanding results. Ten years ago, he did the unthinkable by establishing a large base named the Idofront in the deepest area within the 5th Layer of the Abyss, as well as securing a route to the then-inviolable 6th layer.
During one of his experiments researching the Curse of the Abyss, Bondrewd offered children who wanted to unravel the secrets of the Abyss to come with him to the Ido Front. However, he never openly told them that they were going to be used as test subjects. Among the children were Nanachi and Mitty. As Bondrewd continued testing, more and more children were used up in his experiments until only Nanachi and Mitty were left. On his final test, he used both of them, resulting in Mitty being hit with the Curse of the Abyss, while Nanachi received the Blessing.