We came from the far future, where most of the adults have disappeared as if they vanished into thin air and all of the children are managed by a few adults. To discover the cause behind human extinction and to evade it from that root cause... That's what we had jumped to the past for, supposedly.
A boy sitting in the seats of a movie theater fidgets with his cellphone. "Before aptitude or anything, trying to change the future with just five kids? You would think there's a limit to lack of planning," he typed on his cellphone.
The boys wonder if they had really come to the past. Why? Because, ever since they arrived, they haven't stepped one foot outside this theater.

"I," an aspiring novelist who can’t land a hit, a normal college student. Kai Shouko, a female college student writer who produced a string of hits. During the welcoming party of our university, a naked idiot suddenly barges into my life.

(Source MU)

Ikagawa Togake is a boy with a superpower. He has the the ability to change the color of his eyes whenever he closes and reopens the eyes. Kinda useless, right? Regardless, Ikagawa Tokage strives to strengthen his power in an effort to become the strongest and not have his power be nothing more than a parlor trick. With that desire in mind, he trains daily in an abandoned building in modern day Tokyo. But on one such day, he comes to what looks to be a scene of a crime and feels the culprit might still be nearby. Will he make it out of the abandoned building alive? Is there more to his power than meets the eye?
(Source: Vexed-Scans and Deus-Ex Scans)

In the middle of the school day, on the second floor of the gym.
This is where the two came to skip class, and it's where their friendship began.
A story of two high school girls, playing ping-pong and chatting as they spend the heydays of their youth.

The story revolves around a highschool boy named Niwa Makoto. He lives with his aunt’s family since his parents are away on business. It is there where he meets his mysterious cousin of the same age Touwa Erio — who happens to tie a futon mattress around her upper body and is a self-proclaimed alien. Her staple food is pizza. Erio had been missing for half a year and was found floating in the sea. She doesn't remember anything about what happened during that period of time, but she began to think that it was the act of an alien and wanders the neighbourhood wrapped in the futon.
(Source: AniDB)Note: This includes the extra novel Denpa Onna to Seishun Otoko SF (Sukoshi Fushigi) Han

Adachi and Shimamura, two young women who attend the same high school, are inseparable friends. Whether playing table tennis, chatting about favorite TV shows, or just relaxing together, they’re happy to share their days. When Adachi’s friendship turns into romantic attraction, the relationship begins to change, one day at a time.

(Source: Seven Seas Entertainment)