Tune is a character recommended by BFDIDubita23, and the first ranked recommended character in Insectophobe's Nightmare 3. Tune is seen greatly engulfed in music, or whatever is playing in their headphones. Tune also made an appearance in BFDIA 5b, next to Waffle, where Tune must be used to get the Win Token. Tune doesn't talk very much, according to Waffle.
Tune appears to be an eighth note, a musical note that is half a beat. Tune is black with gray and red headphones.
In BFDIA 5b, Waffle introduces Book to Tune. Match interrupts Waffle, and Book tells her to be nice. Since the game is unfinished, and Tune barely appears and talks, Book's and Tune's relationship with each other are unknown, because they haven't ever directly spoken to each other.