Designated EI-28, Polonaise serves as one of the Four Machine Kings within the Zonderian forces. His Zonder form presents an antiquated figure crowned by a caterpillar-like locomotive engine head. In humanoid guise, he manifests as an elderly, heavyset gentleman clad in a fine suit, his impossibly long hair cascading to the floor. He perpetually wears sunglasses and wields a pipe that emits a train whistle's cry when blown. The Zonder robots he creates consistently feature train or subway-inspired designs.

During the Great Tokyo Upheaval, Polonaise joined forces with fellow Machine King Primarda (EI-29) to energize the expanding Zonder Metal Plant. Their method involved merging with a train to become the combined entity EI-28. This amalgamation was shattered when ChoRyuJin utilized its Power Crane/Ladder to violently collide Polonaise and Primarda. Following Primarda's destruction, Polonaise retreated to Tokyo Tower. Discovered there later, he was purified by Mamoru Amami's abilities, subsequently manifesting in Grecian-style attire akin to inhabitants of the Green Planet before dissolving into the air.

Polonaise and Primarda shared a marriage bond prior to their transformation into Zonderians. Their partnership persisted into combat operations, jointly deploying the gravity-manipulating Zonder Robo EI-20 during an assault on G-Island City.