Miyoko Harada is a young woman introduced as a terminally ill hospital patient in the 2005 film Kamen Rider the First. She suffers from an unnamed but severe disease that leaves her bedridden and isolated, with no one visiting her and her remaining time running short. Despite her own grave condition, she notices that Haruhiko Mitamura, a fellow patient in a nearby room, is in a similarly hopeless and lonely situation. Adopting the guise of a hospital volunteer, she begins to tend to him persistently. At first Haruhiko rejects her attempts to connect, but Miyoko does not give up. One night, when he becomes self-destructive and tries to flee the hospital, her patient and unwavering support finally break through his shell, and he begins to open up to her. She then convinces him to leave the hospital together, and for a brief period they enjoy what feels like a normal day, acting like a couple. During this outing, however, her own illness suddenly worsens, and she collapses. She is rescued by journalist Asuka Midorikawa, who happens to be nearby, and is taken back to the hospital. Miyoko then reveals the full truth of her condition to Haruhiko: her disease is even more advanced than his, and she has very little time left. At that moment, the Shocker Inhumanoid Spider appears in her room and offers her a chance to be cured. Believing his promise, Miyoko agrees to join Shocker, and Haruhiko follows her. Both undergo reconstructive surgery, and she is transformed into the Inhumanoid Snake, while Haruhiko becomes Cobra. As Snake, she gains a serpentine appearance and wears a special combat suit that exposes her mouth, along with a mask. The transformation restores her health but also places her under Shocker's control, binding her to the organization's will. Approximately one year later, she operates as a field soldier alongside Cobra, carrying out Shocker's missions. When Hayato Ichimonji, the second Hopper, is branded a traitor, Shocker dispatches Snake and Cobra to eliminate him. They corner him, but the arrival of Takeshi Hongo allows Ichimonji to escape. Later, when the two Kamen Riders assault Shocker's island base to rescue Asuka, Snake and Cobra lead a force of combatants to intercept them. Miyoko and Haruhiko fight in close coordination, with Snake using her exceptional flexibility and agility to perform acrobatic kicks and strikes. She can also take a whip-like tail appendage that Cobra detaches from his own body and wield it as a weapon. Despite a strong initial assault, the Riders counterattack, defeating the combatants and Bat. In the final confrontation, Snake is struck by a Rider Kick from Kamen Rider 2 and is mortally wounded. She falls at the same spot where, one year earlier, she and Haruhiko had planted seeds and spoken of looking forward to seeing the flowers bloom. A single, fragile flower has now blossomed there. She dies while holding the lifeless body of Cobra, who has also been felled. Her motivation throughout the story is defined by two drives: the desire to survive and the desire to be with Haruhiko. Her decision to accept Shocker's offer stems from the hope of beating her terminal illness, and her loyalty to the organization is inseparable from her devotion to her partner. In human form, she is gentle, patient, and determined, but as Snake she becomes a lethal fighter whose abilities mirror the serpent motif in both flexibility and striking power. Her arc is one of tragic love, beginning in a hospital bed and ending on a battlefield, with the brief promise of a shared future cruelly broken by the very intervention that kept her alive.