Mai Takano is a pivotal character in the horror and mystery narrative of Rasen, which continues the story directly from the events of the Ring cycle. She is introduced as a former student and the romantic partner of Ryuji Takayama, sharing a close relationship with him that involved living together at the time of his death. Her role in the story is significantly expanded following his demise, as she becomes a key figure in the unraveling of a supernatural curse.

Described as possessing a shy demeanor, Mai is nonetheless drawn to the pathologist Mitsuo Ando, primarily because he represents her only remaining connection to her deceased beloved, Ryuji. This attraction is layered with a sense of shared loss and a mutual, bitter loneliness, as Ando is also a man grieving a deep personal tragedy—the drowning death of his young son. While their reasons for coming together are different, their bond forms a central part of the emotional landscape of the narrative, and they eventually become intimate. Mai's core motivation throughout the story is to understand the mysterious circumstances surrounding Ryuji's death, believing it to be linked to a cursed videotape. She seeks answers and aids Ando in his investigation, hoping to uncover the truth about the curse that she feels certain killed Takayama and his family.

However, Mai's role evolves from that of an investigator to a crucial and tragic component of the curse's mechanism. The supernatural entity at the heart of the story, Sadako Yamamura, has a specific design for resurrection. This plan hinges on a woman who is ovulating watching the cursed videotape, as the tape can then impregnate her, allowing Sadako to be born again. Mai becomes the chosen vessel for this process. Unbeknownst to those around her, she is infected with a form of the ring virus that targets her womb, effectively allowing Sadako to conceive herself within Mai. This parasitic relationship allows Sadako to control Mai from within.

The culmination of this horrifying development is the discovery of Mai's fate. After a period in which she disappears, her corpse is found in the ventilation shaft of an unused office building. The autopsy reveals a shocking truth: despite no prior indication of pregnancy, Mai's body shows clear signs that she had recently given birth. It is understood that Sadako, having successfully used Mai's body to rebirth herself, then discarded the husk, leading to Mai's death. Her body is discovered, but the entity that now walks free is Sadako reborn, having used Mai as an unwitting and ultimately disposable surrogate. Mai Takano's journey is thus that of a grieving lover searching for closure, who is instead transformed into a central piece of a monstrous cycle of death and rebirth, her body becoming the instrument for the very evil she sought to understand.