It was not space, nor was it undefined space and time. But that was the world after death. They said dying would feel like sleeping. Then when you wake up from that 'sleep' you realize that you couldn't be reunited with your body.
Some of the moments that occur when the soul broke up with the body may be difficult to explain because several times the human soul wandered while he was sleeping. But it's not dead, not at all.
That feeling of sleep that couldn't be explained well had been felt by Daniel. A child with brown hair that loved monster research, lost family members, and also lost faith in various aspects. He had gone through various experiences that no one else had ever experienced, including fighting head-to-head with a collection of monsters.
But he lost.
It happened very quickly, even in less than a month. Extreme changes and strange things happen in Noland City.