Teenage math whiz Kenji Koiso agrees to take a summer job at the Nagano hometown of his crush, Natsuki. When he arrives, he finds that her family have reunited to celebrate the 90th birthday of their matriarch. His job: pretend to be Natsuki's fiancé. Meanwhile, his attempt to solve a mathematical equation causes a parallel world's collision with Earth.

A new story about the everyday lives and secrets of soldiers, plus Hange's Titan research and the creation of the omni-directional mobility gear.

The daily lives and secrets of the soldiers of the Scout Regiment.