Mizuki Shido is a supporting character in the second season of Gundam Build Divers Re:RISE. She is the older sister of Masaki Shido. Her primary background revolves around caring for her younger brother, who was hospitalized after he failed to regain consciousness while playing Gunpla Battle Nexus Online. This event defines her role in the story: she is the family member left to manage the real-world consequences of her brother’s immersion in the game. Her personality is shown to be devoted and practical, as she remains by Masaki’s side throughout his comatose state, even as the main cast works to rescue him from the digital world. Her primary motivation is the well-being and recovery of her brother, and she acts as an emotional anchor for the real-world stakes of the Eldora crisis. In the narrative, she appears primarily in scenes set in the real world, such as the hospital and later at The Gundam Base when Masaki awakens. Her key relationship is with her brother Masaki, though she also interacts with Hiroto Kuga and the other Build Divers when they visit the hospital to check on Masaki’s progress. Her character does not undergo significant on-screen development; rather, she serves as a reminder of the human cost of the events in GBN and provides closure for Masaki’s storyline. She has no notable combat or Gunpla-building abilities, as she is not a Diver herself. Her significance lies in her familial bond and her role as a caregiver.