Read manga: Dog Days

manga
Other name: ドッグデイズ
Artists: TSUZUKI Masaki
Status: completed
Updated at: Aug 25, 2019
Summary:

Republic of Biscotti faces a predicament by the invasion of Galette Leo Knights. In order to save the country, Princess Milchore summons a "hero" from the outer world. Shinku, a junior high school boy living in the Earth, is chosen as the hero.(source: MAL)