Sago is a water-elemental Enterran, one of the Chosen guiding Yakumo to Shinzo. He embodies the Dragon and the East, his helmet bearing a celestial jewel that unlocks transformative abilities. By invoking "Hydro Power," Sago assumes a Hyper-Form mirroring a water devil, wielding high-pressure water streams and summoning Aqua Dragons. King Nipper later enhances this form, adding bat-like wings and golden accents to his gauntlets and chest.

He allies with Yakumo, Mushra, and Kutal. His early actions include slicing through spider webs to rescue Yakumo and aiding in the carding of the spider siblings. Against Insect King Daku, Sago crafts a plan to infiltrate the enemy dungeon and engineers a diversion using petrol and fire for escape. He later displays tactical skill battling a book-golem construct. During the conflict with Snake King Gyasa, Sago sacrifices himself alongside Kutal, enabling Mushra to absorb their EnCards and become Mushrambo, a pivotal act in Gyasa's defeat.

In Season 2's altered timeline, Sago appears as a gambler, initially dismissing Binka's plea and refusing her offered jewel. He remains with her group only after she retrieves his gambling winnings. When Kadrian beasts capture Binka, Sago's rage activates his jewel, triggering his Hyper-Form to fight alongside Mushra. Though defeated initially, he later reunites with Kutal to form Mushrambo against the Kadrians. Facing Eilis's amusement park trap, Sago deduces the Kadrian strategy to isolate Mushra.

Symbolically, Sago represents the Azure Dragon of the East within the group's Four Gods dynamic, reflected in his blue color scheme and draconic Hyper-Form features.