Merry-san is a supporting character in the anime Re-Kan!. She is portrayed as a ghost who resides in an old, dilapidated school building. Initially, she appears to be a one-dimensional comic relief character, but as the story unfolds, her personality is revealed to be more complex. She has an eccentric and lively nature, often telling jokes and puns, frequently incorporating her own name into the humor. Merry-san is generally cheerful and carefree, not taking herself too seriously, which makes her a well-liked presence among the other characters.

Beneath her playful exterior lies a deeper and more tragic background. It is later revealed that Merry-san was once a schoolteacher who died on the school grounds and has remained there ever since, unable to move on. Her lingering attachment to her former profession is evident in the ghostly tasks she performs, such as ensuring the school building remains clean and free of pests. This sense of duty and devotion underlies her otherwise whimsical demeanor.

Merry-san's motivations center on maintaining the school she cared for in life and occasionally helping the living students she encounters. Within the story, her role is that of a spirit who interacts with the main human characters, particularly Hibiki Amami, who can see and communicate with ghosts. Merry-san often provides comic relief but also contributes to the series' more heartfelt moments, especially when her past is explored. She has a notable connection to a former student, and her development over the course of the series culminates in an emotional storyline involving that individual.

In terms of relationships, Merry-san is friendly with Hibiki and the other ghosts that frequent the school. Her bond with her former student is a key relationship that highlights her growth, as she finally confronts her unresolved feelings from her life as a teacher. As a character, she does not undergo a drastic transformation but rather experiences a gradual and meaningful development that adds depth to her initial comic facade.

Merry-san's notable abilities are those typical of a ghostly spirit: she can appear and disappear at will, move through physical objects, and interact with the material world to a limited degree. She uses these abilities to carry out her self-assigned duties of caring for the school. Her design reflects her whimsical nature: she is a small, chubby ghost with short hair and large glasses, giving her a distinct and memorable appearance. Through her combination of humor and pathos, Merry-san embodies the series' balance between supernatural comedy and touching human drama.