Cetos Orcinus: An Orca Lord. Armed with a sword named the Fatefu Flamberge. He first appeared to halt Palleo from harming Masumi, as he was a follower of the El of the Water. Once partially awakened, the El orders him to kill Majima and Mana. But Orcinus is intercepted by Agito, but managed to overpower him. However, Orcinus was halted by Gills arriving after his revival. The Lord attempted to retreat, but had to fight both Gills and G3-X until he managed to retreat. Orcinus then attempted to kill Shouichi, forcing him to fight the Lord as Agito with Ryo present. The fight ended with Agito Ground Form's Rider Kick destroying the Lord.
OOO, Den-O, All Riders: Let's Go Kamen Riders
To be added