Ushinawareta Mirai wo Motomete: Ushinawareta Natsuyasumi wo Motomete

Yui Furukawa awakens to an unusual July 13, a day unlike any she has previously known. Determined to make the most of her summer break, she joins her fellow Astronomy Club members at the picturesque family villa of Nagisa Hanamiya. This charming location holds a fascinating legacy, having been the residence of Nagisa's great-grandmother, a pioneering scientist linked to the nearby military manufacturing facility.

As the Astronomy Club enjoys their time at the beach, an unexpected storm disrupts their vacation plans, forcing them to seek refuge in the long-abandoned factory. It is within these forgotten walls that they stumble upon a concealed underground bunker, where secrets waiting to be uncovered may hold the key to a future long lost to time.