Jiru Jiru was the Monster of the week on Ep.9 of the UFO Robot Grendizer Anime and was a Mecha piloted by Commander Minao, of Planet Ruby, another world conquered by the Vega Empire. Her actual presence in the show is brief, transforming into robot mode in its first and only encounter with Grendizer, remaining in its Saucer mode through much of the episode and did not have any special abilities besides transforming and a Green laser been been fired from the front end of the Saucer Mode and we don't stick with the Mecha for too long, the episode been character focus on its Pilot, Minao. Jiru Jiru was build in the image of a female warrior: Her arms were colored Light Blue-Green with Purple, and Dark Blue-Green hands. Its legs were Light Blue-Green and Blue-Green, with dark blue-green feet and yellow joints. The lower half of the body and shoulders were blue, while the Torso was red with Blue. It had weapon launchers for breasts, though these are never use. Its body was adorn with light blue fins and its head had a light blue blade shape helmet, with the pilot cockpit located in the forehead, and its face was light green-blue with a red mask and yellow eyes.

Minao arrives on Jiru Jiru to the Vega Moon Base and reports to Gandal and Blacki, who inform her of her mission is a Suicide one, meant to have Jiru Jiru blow up with the Grendizer. Minao is startle by this, but Mrs. Gandal interlude, promising no harm would fall to her home Planet of Ruby and Gandal gives her a Sword as Symbol of the Promise been made. At the Observatory, Daisuke, Koji and the Staff noticed the Moon is glowing red, indicating the sign of another imminent attack, when they detect the Motherburn, Daisuke formulates a plan to capture one of the Pilots to better know their plans. Blacki Launches a fleet of Minifo Attackers to bring Grendizer out: they attack a school, but Koji arrives on the TFO to dispatch them, Duke joins him on the Grendizer and Minao launchers Jiru Jiru.

The Two Pilots make fight, and Jiru transforms in its Robot mode and grabs on to Grendizer, preventing it from leaving the Spacer. Minao activates the Self Destruct, but Duke uses Magnetic Waves, disrupting the Bomb's timer. Grendizer exist the Spacer and Minao is forces to transform back. She tries to attack Duke with a Green laser, but Jiru Jiru is hit with Anti-Gravity Storm, forcing it to crash land in the woods. Grendizer docks with the Spacer and lands, finding Minao unconscious, but she wakes up and attacks Duke, trying to kill him with the Sword. Koji arrives and knocks Minao before she could kill Duke.

She is then taken to Duke's Home where she wakes and meets Prof. Umon. At first, she begs to be killed, but Duke tells her Planet Ruby may had been destroyed (catching her off guard) and tries to convince her to stay to live in peace on Earth... Because when you think to live in Peace on Earth in anime, you make Japan your first choice...

… “Is not like the Islands aren't hit every week by every single catastrophe: some would called it a Death Wish, the Japanese called it Tuesday!”.

Later, Koji brings one of Hikaru's dresses for her: she tries one and meets Danbi, Hikaru, Goro and Bunta. She is invited to dinner and dance party, but her thoughts on her promise make her reconsider and seeing Daisuke's resemblance to Duke, force her to walk out the building and head back to her the ship, where she report to Blacki. After making contact she walks away to have a moment to think, when Daisuke shows up. Minao puts two and two together and concludes Daisuke's true identity which he does confirm. She tries to kill him but is unable to, do to his honesty and kindness.

After returning home, Minao is once again trapped between her emotions for her people and those for Duke and tries to kill him again in his sleep but Duke reacts fast and avoids. Minao expresses to him she is unable to do anything else and runs back to her ship and takes off. Minao encounters Blacki and she begs him to let her be, but viewing her escape as treason, the Motherburn fires at her ship. Grendizer arrives and tries to protect her, but she is shutdown by one the lasers and crashes near a beach. Duke exacts his revenge on the Motherburn and the Minifos, and Blacki is forced to retreat.

Later, Duke extracts a mortally wounded Minao from the smoldering wreck of the Jiru Jiru: she wakes up and smiles at him, saying a few words to Duke about her home world before passing away as her ship explodes. Still holding onto Minao, Duke promises to fight on for Planet Ruby in her memory.