|This article is about a/an character in Kamen Rider, the original series as well as Kamen Rider Ghost.|
Mayu Tachibana (立花 麻由 Tachibana Mayu) is Tobei Tachibana's granddaughter, who is studying in the attached school of the Jounan University. She is targeted by Shocker and Nova Shocker. At an unknown point, she is taken over by an Alexander Gamma Eyecon.
The grand-daughter of Tobei Tachibana, her parents had died prior to the film and was abandoned by Takeshi Hongo three years prior. While studying at the Jonen University High School, she worked and lived by herself. Later she becomes the target of Shocker and Nova Shocker for reasons unknown to her.
After saving her from an attempted kidnapping by Shocker and Nova Shocker, Takeru and the others try to find out why she was targeted, Takeru going undercover as a student teacher at Jounan University to find out more about her. With Takeru beginning to fall in love with Mayu instead, Akari quickly replaces him and investigates herself. During class, Mayu suddenly collapses before briefly taking on a booming voice and ordering everyone away from her. Akari tries following up on this with Mayu after class when Takeshi Hongo saves them from another Shocker attack. It is revealed that Hongo had promised to look after Mayu after her parents had died until she was an adult, and she was angry at him for suddenly leaving after that three years prior. She said she would forgive him if he would make up those three years of birthdays, which he did. Hongo reveals that when he had been fighting after leaving her, he had always felt like he was fighting to protect her; she forgives him for leaving, and be decides to stop fighting and instead watch after her again.
When Nova Shocker overloads Japan's power grid, Takeru, Akari, and Onari find Hongo and Mayu in a cabin in the woods, but he refuses to fight with them again; it turns out he knows his body is giving out, and had come back to see Mayu again while he still could. However, a revived Ambassador Hell arrives and captures Mayu, revealing that her outbursts and Shocker's interest in her were because she contains the Eyecon of Alexander the Great, placed there by the Ambassador at an unknown point prior so that it could mature into its full power; Mayu was selected because of her blood relation to an "indomitable man" (it is unclear if the Ambassador meant Alexander the Great himself, or Tobei Tachibana, who had been similarly described earlier in the film). Nova Shocker then attacks, and while the Ambassador successfully extracts the Alexander Eyecon from Mayu, Urga instead claims it, punching the ground and releasing an energy shockwave; Hongo grabs Mayu to protect her and is slammed into a cliff wall by the blast, the impact killing him.
Mayu, Takeru, Akari, and Onari later light a funeral pyre for Hongo. Mayu says she won't cry before telling the others to leave. She breaks down crying, begging him to come back. At that moment, his belt opens and the pyre bursts apart, a massive flame cloud forming the shape of a phoenix, and Hongo steps out of the flames. Knowing it was his connections with everyone's hearts that brought him back, she told him to go and help the other Riders against Nova Shocker again.
In the end, Mayu allows Hongo to go off fighting evil again, knowing that wherever he's fighting, he's protecting her, as all lives are connected.
Mayu Tachibana was portrayed by Natsumi Okamoto (岡本 夏美 Okamoto Natsumi).