_Concept_ Quadimension distributed a postcard featuring Haiyi with a description written by ATDan on the back. According to ATDan, "Haiyi was born by sea. The waves and marine animals tell the story of the girl who was born of the sea. The Metatron's Cube symbolises the relationship between Haiyi and water, the gem on her necklace is of the same space. This girl doesn't just look like the sea, her voice is like the water too: gentle and elegant. A sound like water, an appearance like the sea". For Haiyi's logo, a shape known as the icosahedron is present next to her name and is part of the last three strokes in the "海" character. In the spiritual meaning of Metatron's Cube, the icosahedron represents water, which influenced her design, name, and concept. In March 2019, Haiyi was revealed to be part of the Medium⁵ cast and was one of the girls who derived from a single being known as ZERO who possessed Metatron's Cube. She was listed as a Cancer sign. According to the Dreamtonics website, Haiyi is described as chatty and mischievous. _Appearance_ Haiyi’s design follows an ocean theme. Her color scheme consists of light and dark blues, whites, and pinks. She wears a jellyfish on the left side of her head. ATDan explained that because Haiyi was born by the sea, he designed her with clear blue hair and eyes (mentioning that the sea gave them to her). Her clothing was based on the outfits worn by ice skaters and her shoes signified waves moving around. The jellyfish and the symmetrical tailfin gave an impression of a sea god in ancient times.