Miyuki Aiba is the younger sister of Takaya Aiba, the protagonist who transforms into Tekkaman Blade, and his twin brother Shinya, who becomes Tekkaman Evil. She is the youngest child of Dr. Aiba Cozo and was originally part of the Aiba family that crewed the exploration ship Argos. When the family discovered a dormant Radam mothership near Saturn, they were captured and forcibly converted into Tekkamen. Because Miyuki’s body was not strong enough to become a fully functional Tekkaman yet not weak enough to be immediately consumed, she was rejected by the Radam and left in an incomplete state. This incompleteness allowed her to retain her free will and escape to Earth in her Tekkaman armor, carrying the critical secret of the Radam’s invasion plans. Her primary motivation is to warn her brother Takaya about the true nature of the threat and to reunite with him. She is also driven by love for her family, as evidenced by her attachment to her favorite flower, amaryllis, which later becomes a poignant memory for Takaya as he loses his recollections. Although she arrives on Earth safely, she is immediately hunted by her own brother Shinya and three other enemy Tekkamen: Lance, Axe, and Sword. Realizing that she is outmatched and that they intend to kill her to prevent her from aiding Blade, she makes the ultimate sacrifice. She self-destructs in an attempt to destroy all four of them, a desperate act that ultimately fails to eliminate them but underscores her bravery and selflessness. Her sacrifice deeply affects Takaya and serves as a catalyst for his emotional development. As Tekkaman Rapier, her armor is red and white with a v-shaped visor and a green gem on the forehead, and she wields a thin rapier that can extend wires. She is classified as a scout and information-gathering type rather than a front-line combatant, emphasizing a support role among Tekkamen. Her incomplete transformation means her physical abilities are lower than those of full Tekkamen, yet she still manages to fight briefly before choosing self-destruction. In the larger narrative, Miyuki’s brief but crucial role provides vital exposition about the Radam, deepens the tragedy of the Aiba family, and highlights the emotional stakes of the conflict. Her memory continues to haunt Takaya as he struggles with his gradual amnesia, making her a lasting symbol of the family he lost.