According to Moonphase Diary and the wraparound jacket found on reprints of the novel, an anime adaptation of Tsukiji Toshihiko’s light novel 「Kenpufer / けんぷファー」 is in the works. The series originally began in November of 2006, and has spawned 9 volumes to date. It was later adapted as a manga and published under the seinen magazine, Monthly Comic Alive.

*Description courtesy of Manga-Updates:

Kampfer – One who exists to fight. Anyone chosen as a Kampfer will be forced to fight until death. Our hero, Natsuru-san awoke to find himself chosen as a Kampfer. Only one thing for him changed. He is now a She!

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