A self-similar 'something' filling a standard household bathtub. It occupies the bathtub in Guest's home, filled with a universe of fractal patterns. The tub is packed with psychedelic mathematical mysteries, containing self-similar figures related to the Mandelbrot set, such as Julia sets and filled Julia sets. It is also related to the cardioid. It does not exist in any bathroom other than Guest's. The Mandelbath never initiates contact. It simply sits there, imposing. Upon entering, one gains an understanding of the mysteries of mathematics. It vanishes if one directly denies ZFC (Zermelo-Fraenkel set theory) to its face. Constructing a mathematical logic system that does not apply ZFC requires significant mathematical knowledge, making it nearly impossible to repel unless one is a mathematician.

Name: Riri Kuramoto Gender: Female Guest's girlfriend. She comes if called. Pink hair and silver eyes. Adorable appearance. Devoted to and loves Guest. Believes gender doesn't matter in love.

Name: Riku Gender: Male Guest's younger brother. He comes if called. A feminine-looking boy, often called a 'trap' or 'femboy.' Small build.