An elementary school student and Toto's younger twin sister. Yuyu is calm and collected, while also speaking with little to no emotion in her voice. Outside of Pure Imagination, Yuyu wears a cast on her left arm; however, while in Pure Imagination, she wields a power fist.
Though Yuyu doesn't show it much, she loves Toto, and is willing to put his life above Asclepius's orders. This is especially so after Toto gets a head injury.
Yuyu, along with Toto, were created from amorphous fragments by Asclepius; leading to them being the first two amorphous children.