Zenranium appears as a mostly nude vampire, his groin perpetually obscured by a cluster of geranium flowers. He possesses black hair and a distinctive black cape lined in red, designed to resemble a blooming flower.

Despite his unusual appearance and habit of spreading seeds, Zenranium exhibits a notably passive demeanor compared to other Shin-Yokohama vampires. He frequently presents sound, logical arguments relevant to any situation.

His core ability is plant manipulation, enabling him to control flora and any individuals who consume his seeds. Those ingesting the seeds develop geranium clusters on their groin; women manifest additional clusters on their chest.

Zenranium is frequently imprisoned at the Vampire Research Center (VRC), detained alongside vampires Ydan Ojisan and Yakyūken Lover. During confinement, he shares quarters with entities like Vampiric Garlic. Kazura, a VRC caretaker, oversees him and the other detained vampires.

Documentation inconsistently records his real name as either Naekida Mamoru (苗木田 葵) or Tenjiku Mamoru (天竺 葵).