Tomoko is the twin sister of protagonist Kujaku, separated from him during their childhood in Tibet. A Neo-Nazi cult raised her, recognizing her as the incarnation of the Rahu deity (also known as Tenjaō or the Snake Queen) and seeking to exploit her latent spiritual abilities as a weapon. They embedded her within their ideological framework from a young age.
Her spiritual significance lies in being one of two key reincarnations destined for an apocalyptic ritual. Prophecy dictates that the Rahu (Tomoko) and the Peacock King (Kujaku) must battle to birth the dark cosmic entity, the Dark Vairocana, driving the narrative's primary conflict.
Tomoko's relationship with the sorcerer Huang Haifeng (Kō Kaihō) becomes pivotal. His love for her leads him toward darkness as he attempts to intervene in her fate; ultimately redeemed by Kujaku, Huang Haifeng marries her. Their union results in the birth of a son, concluding her familial arc.
During the events of the OVAs, *Revival of Evil* and its sequel, Neo-Nazis abduct Tomoko to harness her connection to the Dragon Orb—an artifact linked to ancient gods—for their regime. This culminates in a climactic battle on a Tibetan plateau where Tomoko, under her captors' influence, confronts Kujaku. Their struggle involves projecting giant spiritual avatars representing the Rahu and Peacock King entities, fulfilling the prophecy's foretold ritualistic confrontation.