Yoka Nakatomi began as a human living on Agano Station, sharing a close friendship with Shizuru Chikura. Their bond broke over a disagreement concerning Yoka's dream of becoming an astronomer, leading her to leave for Ikebukuro.

The devastating 7G Incident transformed Yoka into a powerful witch queen with reality-manipulating abilities. She used these powers to rule Ikebukuro, though they steadily consumed her life force.

Pontaro, the inventor of 7G, erased Yoka's memories to hide the technology's catastrophic failure. He manipulated her into serving as a figurehead ruler while exploiting her powers to eliminate witnesses who threatened to expose the incident's truth. Under his control, Yoka enforced Ikebukuro's isolation, deploying entities like Chaos to bar outsiders.

Pontaro's memory suppression specifically targeted Yoka's past connection to Shizuru and their shared history in Agano. When Shizuru and her companions reached Ikebukuro, they triggered events that restored Yoka's original memories, breaking Pontaro's hold over her.

Liberated, Yoka employed her reality-altering powers to reverse the 7G Incident's global effects, restoring transformed populations and landscapes. She then returned to Agano alongside Shizuru and the others, ending her tenure as Ikebukuro's witch queen.