Kyon's Sister

キョンの妹

Little is known about Kyon's fifth-grade sister; her real name is not even provided. Other characters simply call the eleven-year-old Kyon's (Younger) Sister or Little Sis. She has relatively few lines, although she appears in The Adventures of Mikuru Asahina - Episode 00, Episode 6, and Episode 14, acting as an irrepressible younger sister. In the original novels, she has even fewer lines and appearances than in the anime adaptation. Usually, her presence is noticed whenever Kyon is at home.
She is carefree, happy, and playful, and she is also responsible for the use of the nickname "Kyon"; after hearing their aunt call her older brother that, she began using the nickname in front of his school friends. From there, the name spread and eventually stuck. She seems to get along well with all of the SOS Brigade, especially with Mikuru, with whom she shares a sister-like relationship.