It is time for them to return home.
After saying their goodbyes, the Yurans returned to their respective hometowns. The lone dragon princess said she'll go on a journey to look for more delicious food, and thanked everyone for the all the unforgettable experiences over the past 15 years. And all the food, of course. The three Idearns stayed to keep the base operational, just in case something bad happens in the future. All of them swore to meet again someday. Their bodies no longer experience senescence, so though it may take a while, they'll surely meet again.
The unfinished Idearn secret model was dismantled before their departure, and all research related to it were permanently erased.
And that is the end of their journey.

Happy birthday!