Zero no Tsukaima (the Familiar of Zero) was a series of light novels that were turned into a popular, multiple season anime series. There were also dozens of spin off novels and side stories he wrote.
He passed away on April 4th, at age 41, due to advanced cancer.
Although he never finished his final two novels, the anime series was completed hurriedly last year and has a solid, satisfactory conclusion. If you've not watched the series, it's kind of a cross between Harry Potter and Fairy Tail, with a wizard's academy, taking place in an alternate world connected to Earth. (I like to assume that during the middle ages, Founder Briml sent all the witches back in time 6,000 years at the same time they abandoned France to avoid too many questions when the inevitable dimensional crosses happened.)
Edited, Apr 15th 2013 11:02am by Catwho