Diamond Master Oz

is a Japanese light novel series written by Ei Sueba, with illustrations by Tea. The series began publication on March 10, 2012 by ASCII Media Works under their Dengeki Bunko publishing imprint.

Synopsis
Time is the era of mass excavation of jewels (jewelry rush) ─

─ With the discovery of the huge jewel "heart of the world", the world and the life of a man will undergo a major transformation. Oscar Oswald, the last jeweler who cut the "heart of the world" using "Light Even", one of the seven masterpieces. He drove his best friend, the humanoid heavy machine (Stein) D Rampage, on a vengeful journey in search of his soul.

However, under such Oz, a beautiful girl who claims to be "Yuishimin" and an android girl appear ...!?