Worldbuilding words to episode 4, please read the episode before you read this, link in the description.

How does this time shield working? 

In fact, it is not the shield that does that, it is the blue light that did she come out from the hidden forest, but she does not know that yet...shhh

So when the shield comes up, she has taken a piece of the hidden forest with her, and in her place the time does not go. That why, when she stepped out the real-time she binging older. But because the time is stopped on her will all that cross into the shield be younger like her.

Please go back to the story and read ep. 5 before you continue the worldbuilding, link in the description.