After completing the task, Hiro didn't stay there much longer. He was planning a shelter relocation, meaning that he wanted to bring his shelter here by moving the mountain that his shelter was located in.
Hearing Hiro's plan, Saya immediately accepted it. She also wished to change the shelter location, the previous site seemed a bit dull other than the overly stretched expanse of underwater forest.
Nothing worth mentioning and the view was barely okay.
And now that they have a better place to settle in, why not do it?. It is better here in all aspects, especially the people and the city.
If something were to happen to the city, at the very least Hiro doesn't have to fly all over the place just to protect it. The closer the distance, the better the protection would be.
Added to that, Hiro also instilled some of his energy inside Ilon's body. Hiro did this just because he wanted to make sure that this old man doesn't have any second thoughts about his idea.