Wizard's Brain

is a Japanese light novel series written by Reiichi Sigsawa, with illustrations by Jun Keiichi. The series began publication on February 10, 2001 by ASCII Media Works under their Dengeki Bunko publishing imprint.

Synopsis
Mankind was on the verge of extinction due to the runaway and war of the atmospheric control plant. Amagi Ren, a boy of "Magician" who manipulates even the laws of physics by rewriting the "information" of existence, is an experiment to be transported to Kobe City, one of the only seven closed cities "City" left in the world.

He receives a request to take a sample, but is also blocked by the magician "Knight" Yuichi Kurosawa and brings back only a girl named Fia. Ren and Yuichi collide with each other for the people who want to protect them. However, Fia had a serious secret about "City" ...