Ooyama Kenzou leads Eternal Earth as CEO, a UN-commissioned corporation building Neo Jungle, an artificial nature preserve. This initiative forcibly relocated wildlife into a manufactured habitat to combat 21st-century environmental collapse. Ooyama declared himself the "creator of nature," seeking ecosystem domination and explicitly stating his goal to "become the creator of all life and replace God."

His relationship with son Kenichi—who understands animal communication—remained strained. After catching Kenichi secretly entering restricted B-Block, Ooyama confined him. The next day, Ooyama triggered a system reset in B-Block, igniting an uprising among elephants, zebras, giraffes, tigers, hippos, lions, and other animals led by lion cub Leo. Amidst the chaos, Leo attacked Ooyama while carrying Kenichi’s phone, compelling Ooyama to recognize his duty to protect his son. An explosion then rendered Ooyama unconscious.

Ooyama nursed an unspecified vendetta against Toto the panther and hostility toward other animals, intensifying after a virus infected Elder Dolf, who was transferred to an Ooyama-supervised lab. When Neo Jungle collapsed during the revolt, animals returned to the wild, and a hippopotamus dragged Ooyama away.

Records acknowledge his connection to Dr. Mustache (Mr. Pompous), though their relationship’s specifics remain undocumented.