Ihika emerges in 2055 as a Tokyo businessman within Shinjuku Ward, encountering Rin Asougi during her amnesiac period under the alias Tamaki Saito. A romantic bond forms between them. He proposes marriage but is initially refused; a second proposal later gains Rin’s acceptance, followed by intimacy. Their union shatters when assassin Laura strikes, killing both simultaneously.

Reborn as an angel within Apos’ castle, Ihika conceals his identity behind a mask. Rin battles this anonymous angelic foe and slays him. Recognition dawns only post-combat when she discovers Ihika’s corpse and identifies a unique chest tattoo.

This metamorphosis from human to angel intertwines with overarching mythological forces of Yggdrasil and time fruits. Ihika embodies tragedy, enduring layered losses: violent mortality, irreversible angelic transformation, and final obliteration by Rin’s unaware hand. His arc exemplifies the series' recurring motif of doomed immortal relationships.