Horobi (滅 lit. "Destruction") is the Humagear acting leader of MetsubouJinrai.net who transformed into Kamen Rider Horobi (仮面ライダー滅ホロビ, Kamen Raidā Horobi) but was forced to become the first (and later primary) host of the Ark as Kamen Rider Ark-Zero (仮面ライダーアークゼロ, Kamen Raidā Āku Zero) and later the Massbrain System as Kamen Rider MetsubouJinrai (仮面ライダー滅亡迅雷, Kamen Raidā MetsubōJinrai).