Board Thread:Questions and Answers/@comment-35973148-20180624090727/@comment-27973430-20180716183834

Miseng isn't actively aging, the changes in her appearance is the result of SIU's art style evolving since her first appearance.

As for her actual age I can't say because I don't think it was ever stated, though I could be wrong. So she could look her actual age or she could be like Anaak and Ran. Considering that she is part of the same generation as Goseng there is a good chance that she is of a similar age to her.

And time doesn't move faster in the tower. Because everyone in the tower lives for so long their perception of time is different from the people in the real world so 7 years to them is like 2 years to us.