Laplus is a supporting character in Kamitsubaki City Under Construction. Laplus is a rare type of being known as a tesseracter, a creature born from human negative emotions. Unlike most tesseracters, which are hostile monsters, Laplus chooses to side with humans. In their true form, Laplus appears as a massive blue fish. When interacting with humans, Laplus adopts a disguise that resembles a short boy with white hair and red eyes. Their personality is cool-headed and sarcastic, and they are described as eccentric. Laplus keeps their inner thoughts guarded, but they are motivated by a desire to protect the main protagonist, Kafu Morisaki, for reasons that remain unclear. Laplus plays a crucial role in the story by rescuing Kafu early on and revealing to her that she is a witchling, a person whose singing can destroy tesseracters. Throughout the series, Laplus acts as Kafu’s guide and protector, fighting alongside the witchlings against other tesseracters and assisting in the defense of Kamitsubaki City. The key relationship Laplus maintains is with Kafu, whom they watch over closely, but they also interact with the other witchlings. Laplus’s development is limited; they remain a steadfast ally without a major personal arc. Notable abilities include the power of acceleration, which allows them to move at high speeds, and the capacity to create cloned copies of their own body. Laplus is also one of the few tesseracters capable of independent thought and loyalty to humans.