I didn't realize this earlier but I apparently missed the scene where Kai meets Gaia and asks for her answer.
If I didn't back-read now, that scene would have probably been buried under many things and would have never come.
So without further ado, here it is.
***
"So have you thought about it?" Kai asked as Gaia gulped.
After leaving Fanglin back at Kosma's place, Kai was on the land of earth in the elven realm to hear Gaia's reply.
She on the other hand was trying not to make eye contact with Kai but it wasn't working well.
So she instead took a deep breath and stared at his hair.
"I am ready to help the spirits but I have no idea whether I will follow you after that or not." She replied while nervously moving her hands as Kai smiled.
"It's your decision Gaia, not mine. If you want, you can stay here and I will go back. But if you really want to save those spirits, then I will take you with me."