I think that Hyuntae's and Eunhwa's ages are revealed, and there might be revealed ages of characters from Season 1 somewhere (though I'm not sure, I didn't see it anywhere), but I'm sure that I didn't see Shiho's age for example written anywhere and I'm kinda curious, will you reveal them or they'll stay a secret? (I don't mean right now but maybe somewhere in the future updates of new season or maybe on forum, like facts about characters and so on.) Thanks for the reply. :)
Natara 
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Hello zeroonii,
You can check out the White Island characters' age and introduction that are currently revealed from the following link:
http://wi.visualshower.com/index.php?mid=intro_s2&l=en
However, we sincerely ask for your understanding that it is difficult for us to reveal the age information of the characters that are unrevealed in the above link.
We will make sure to announce any updates and recent news regarding the character information through our official forum page!
Thank you.