- Disambiguation: not to be confused with C³-bu, which began as a manga in 2010.
C³, also known as C Cube (シーキューブ, Shīkyūbu) or Cube×Cursed×Curious, is a Japanese light novel series that began in 2007 written by Hazuki Minase and illustrated by Sasorigatame about Haruaki Yachi who receives a mysterious black cube from his father. That night, Haruaki is woken by a noise and finds a nude girl named Fear in his kitchen. In 2011, it was adapted into a manga and anime series.
The story begins with high-school student Yachi Haruaki receiving a mysterious package, a super-heavy black cube from his father overseas. That night, Haruaki wakes to a suspicious noise in the kitchen and discovers a stark-naked female stealing rice crackers. The girl Fia, or “Fear”, is the first of several surprises that Haruaki is to receive.