Shiki Mikage, adoptive sister of Remu Mikage, engaged in an advanced neural-linked nanomachine program enabling consciousness uploads into cyberspace while physical bodies remained preserved in "body pools." As a student in Okinotori Island Mega Float City, she leveraged this technology for academic efficiency, revealing to Remu that her digital communications were artificially generated.

During the global "Early Rapture" system failure, network overload triggered mass consciousness loss. Presumed comatose or deceased like thousands of others, Shiki’s physical body later awoke devoid of familial or past memories. The emergent consciousness inhabiting her form identified as separate from Shiki, adopting the name "Poem"—derived from Shiki’s name—and asserted origins from another body.

Poem demonstrated unexplained nanomachine manipulation abilities, drawing pursuit from unidentified researchers. Though occupying Shiki’s form, Poem retained no memory of her true identity, navigating a quest for answers while evading capture. Remu allied with Poem to trace her origins and recover Shiki’s consciousness.

Shiki’s scientific lineage saw her following parental research footsteps before the incident. Post–Early Rapture, her physical form became a nexus of conflict and mystery, propelled by Poem’s struggle for survival and self-discovery against external threats.