Kurumiru is a supporting character in The Seven Deadly Sins: Grudge of Edinburgh. She is a very young and diminutive fairy girl who originally lives in the Alpa Forest. Physically, she is small, with purple hair styled in two pigtails, a pair of small pink insect-like wings on her back, and eyes drawn as three simple horizontal lines. She wears a short white dress decorated with pink bubble-shaped markings.

During the events of the film, Kurumiru and other non-human children are captured by the forces of Deathpierce, the former Holy Knight who is hunting fairies, demons, and giants for his chimera experiments. She is taken to Edinburgh Castle and held prisoner there. When Tristan and a mysterious fairy arrive to fight the Empties and break into the castle, Kurumiru and the other captives take advantage of the chaos to free themselves. Alongside companions named Gandf and Recela, she flees from the castle while Tristan and the fairy promise to save those still locked up.

Kurumiru’s personality is not explored in depth due to her minor role, but her brief presence conveys the fear and vulnerability of an innocent child caught in a dangerous situation. Her motivation is simply to escape captivity and return safely home. She has no notable combat abilities or special powers beyond the natural fairy trait of flight using her small wings. Her key relationships are limited to the group of rescued children she flees with; she is not closely connected to any of the main heroes. There is no significant development arc for Kurumiru in the story. She functions primarily as a face of the innocent non-human civilians whose suffering gives weight to the rescue mission, reinforcing the threat posed by Deathpierce to the fairy and other non-human clans.