A light novel adaptation with four chapters was published by Kadokawa Shoten, and serialized in the Newtype magazine between March and July 2011 issues.
Kadokawa Shoten also published a Dog Days manga illustrated by Takuya Fujima, which serialized in three different magazines from May to November 2011.
Shinku Izumi is a cheerful and athletic half-Japanese, half-Cornish boy who studies at Kinokawa International School in Japan, and has a normal life everyday until he suddenly got summoned to the alternate world of Flonyard (フロニャルド, Furonyarudo).
The one who summoned him is Millhiore, the dog-like Princess of the Biscotti Republic (ビスコッティ共和国, Bisukotti Kyōwa-koku), who requested his assistance against the forces of the feline-like Galette Lion Dominion (ガレット獅子団領, Garetto Shishi Danrei).
After responding to Millhiore's plea, he receives a sacred weapon, the Palladion (パラディオン, Paradion), and is appointed as a Hero to fight for Biscotti in a war that, unlike the ones on Earth, is waged with special rules and no casualties, in a fashion similar to a sports competition with the purpose to raise funds for the Kingdoms involved, where the winner faction claims a larger sum than the losing side.
After winning his first battle for Biscotti, Shinku learns that when a hero is summoned into Flonyard he becomes unable to return to his homeworld, a fact that Millhiore also was unaware of.
After successfully returning home, Shinku is summoned back time and again (when the conditions were met), to visit Flonyard while embarking freeload adventures with them, accompanied by his cousin and rival athlete Nanami Takatsuki, who is chosen to become Galette's Hero, and his close friend Rebecca Anderson who is also chosen by the squirrel-like Principality of Pastillage (パスティヤージュ公国, Pasutiyāju Kōkoku) to become their hero as well.
The anime series, produced by Aniplex and Seven Arcs,[3] is directed by Keizo Kusakawa, series composition by Masaki Tsuzuki, character designs by Osamu Sakata, music by I've Sound, Maiko Iuchi, Susumu Natsume and Yui Isshiki, and produced by the production company Project DD.
A guidebook to the series, called Dog Days: Memory of Flonyard, was released by Kadokawa Shoten on January 26, 2012.