Mahiru Saginomiya

Mahiru Saginomiya (鷺ノ宮まひる) was a girl that appeared in Ultraseven X 100 years ago prior to the series.

Ultraseven X
100 years ago, Saku and his younger brother, Nozomu stopped at the Saginomiya household area to seek a temporary refuge, after journeyed through various places on Earth. Nozomu fell in love with Mahiru Saginomiya as she's the same vice versa but unfortunately, everyone around her protested their relationship and their marriage plan. Nonetheless, Nozomu swore that he will always stay by her side. After Mahiru realised that Nozomu was fear of water, she determined to know so much about the secret and to do it, she tricked Nozomu to get the water lily from her household pond. Unfortunately, this became her undoing as it transformed him into Jyuujin and killed her before he ran away into the underground tunnels and slumbered.

Her action would lead Jyuujin into becaming a murderous killer whom hunted down people with Mahiru's lookalike without accepting the fact that he had killed Mahiru. After detected by DEUS agents, The monster's rampage would finally end when Jin/Ultraseven X killed him via his Eye Slugger.

Trivia

 * Mahiru was similar to Asami Agata from previous episode of Ultraseven X as both of their death was made by their loved ones unintentionally and they became murderous killers while denying the fact of their lover's death.