Jojo's Bizarre Adventure 2 Part 9: The Jojolands (Japanese Edition) by Hirohiko Araki

[Volume 2 Part 9] The owner of the six-million-dollar diamond is none other than manga artist Rohan Kishibe. When Dragona and the others are discovered inside his mansion, they launch a Stand attack--but are swiftly and overwhelmingly defeated. As if that weren't enough, the diamond itself holds a bizarre mystery... one that makes it impossible to steal. What is the true nature of this object...!?