From the New World

From the New World (新世界より) is a Japanese novel by Yusuke Kishi, originally published in 2008 by Kodansha. It received the 29th Nihon SF Taisho Award. The novel has received a manga adaptation in Kodansha's Bessatsu Shōnen Magazine, which was serialized between May 2012 and June 2014, and an anime television series adaptation by A-1 Pictures, which aired in Japan between September 2012 and March 2013. The manga series has been licensed by Vertical Inc and the anime by Sentai Filmworks in North America.

Plot
Saki and her schoolmates enjoy what they consider normal lives in a peaceful provincial setting. Only their village cannot be of this era. Its customs differ from those of any known in modern day Japan. The landscape while familiar is also much more constrained than what modern day maps may exhibit.

So when 6 friends embark on a journey of mental and physical training, this fateful journey will lead them to a series of mind-shattering truths-for these characters and for us as readers.

Official

 * Wikipedia's article about the series.
 * Anime official website