kyons sister

Not much is revealed about Kyon's fifth-grade sister; not even her real name is provided. Other characters simply refer to the eleven-year-old as Kyon's (Younger) Sister or Little Sis. She has relatively few speaking lines, though she does appear in The Adventures of Mikuru Asahina - Episode 00, Episode 6, and Episode 14, embodying the role of an irrepressible younger sister. Her appearances and lines are even more limited in the original novel compared to the anime adaptation. Generally, her presence is felt when Kyon is at home. She is carefree, happy, and playful, and she is responsible for popularizing the nickname "Kyon." After overhearing their aunt call her older brother this, she began using it herself, especially in front of his school friends, which led to the nickname catching on. She appears to have a good relationship with all members of the SOS Brigade, particularly with Mikuru, with whom she shares a sister-like bond. Source: Wikipedia