Time Travelers from Level-5 is set in Tokyo during 2031. But it has now been revealed that the game actually starts only a few years in the future until a hole, referred to as the “Lost Hole” opens in the sky above Tokyo. This is accompanied by an explosion and Central Tokyo is destroyed and many lives are lost. This is when the story then jumps ahead to 2031.
There’s no specific details about how the story unfolds, although andriasang provided the following details about the futuristic setting:
"Tokyo is a futuristic city, with holographic signs filling the streets, and a building called the “Space Elevator” rising from Tokyo Bay. While there’s a “space” in the name, the building is only 2,000 meters high. It serves as a power source for the city."