Quick version from what I can figure out:
Adult Jiu gave ball to 6 Yr old Tokiwo.
6rs old Jiu gets swapped with other 6 Yr old Jiu from different reality due to the ball. And the adult Jiu.
When 18 yr old Jiu gets swapped they went to their original worlds.
Then not knowing they go back to their 'home' world.
Then realise and swap back after 8 years when they started to disappear as its not their real world.
All so another Jiu and Tokiwo from separate worlds who love each other could be together.
This is the Same I understood, I was confused because of the third couple of Jiu and Tokiwo but after I read it a second time (many years after) I got it.
Me: reads the second story for the 5585858 time
Also me: still doesnt get wtf its happening
#－.－)