C³, also known as C Cube (シーキューブ, Shīkyūbu) or Cube×Cursed×Curious, is a Japanese light novel series written by Hazuki Minase, and illustrated by Sasorigatame. C³ is about a high school student named Haruaki Yachi, who receives a mysterious black cube from his father who is overseas. That night, Haruaki is woken by a noise and is surprised to find a girl named Fear Kubrick in his kitchen eating rice crackers. Haruaki confirms that she is the cube, but knows nothing about her past other than that she has a curse on her which she wants broken. Breaking the curse though proves hard as there are organizations that seek to capture or destroy Fear, along with her dark past as a "Cursed Tool" which comes to light. Haruaki vows to protect her though, and is joined along by other allies/friends as the series progresses.