
Shin is older than Wolfgang (said by Haga on twitter) and at chapter 1 Wolfgang is approximately 13 years old. But there's also some unspecified time skips in the story.

shin must be like 14

I think Shin is 14 since..
(S.P.O.I.L.E.R)
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The King will not sleep with anyone under 15 because of something, and then later he wants to sleep with Shin eventhough he isnt 15 yet. ("Dont worry I wont hurt you" my Ass!!)
Wait the Prince is younger? He is 13 then? Wooooooowww he isnt that innocent since he can do "that"
how old exactly are they..?