What does the first episode of Destiny's Stone Gate mean?

In the first episode, the man witnessed Christina's death and sent an email to his friend. But because of the telephone microwave oven he inadvertently made before (the actual function is time-space jump), the man jumped directly to another world through email. In that world, Christina was alive, and then in that world, the man and Christina jointly created a time-space jumper (in the true sense), but in that world, Makoto's death was certain, so that person started to jump in time and space in order to save this ending, but once he jumped into the world where Makoto would not die, Kristia's death was inevitable, so the man's rescue was reopened, and the door of destiny stone was undoubtedly originally written.