Author Yamaguchi Noboru posted on his Twitter that he has been writing Zero no Tsukaima novel while under treatment for the terminal cancer. He disclosed the illness last July and took a surgery last August. He said he lost his hair due to the side effect of the anti-cancer drugs. The side effect of the drugs prevents him from writing for two-thirds of the month and he works slowly during the rest of the month. He said he wondered if it's better to stop writing the novel because he could not work with his full strength but he decided to deliver the novel to the readers since that's the only thing he can do and that's his everything.

Source: Yamaguchi's Twitter account