Mio is a maid and bodyguard who serves Yura in the underwater kingdom of Kaien. She was created as an original character for the film That Time I Got Reincarnated as a Slime the Movie: Tears of the Azure Sea. Alongside a fellow maid named Yori, Mio is tasked with protecting Yura as she flees from the kingdom of Kaien and makes her way to the surface world. Her primary motivation is to ensure Yura’s safety, and she fulfills her role with quiet dedication. Mio’s background is not explored in depth, but her position suggests she is a skilled protector trained in the ways of the oceanic realm. She does not undergo significant personal development over the course of the story, instead remaining a steadfast supporter of Yura’s mission. Her notable abilities are not explicitly detailed, but she is capable of defending Yura against hostile pursuers and navigating the journey from the sea to the surface. Mio’s relationship with Yura is one of loyal service, and she works in close coordination with Yori to carry out her duties. Her role is primarily that of a supporting character who helps advance Yura’s story arc and contributes to the group dynamics during the film’s events.