Responses

Author never specified age but in Chapter 20 Count Rothsildt guesses that Ian might be 17-18 based on his appearance: http://www.mangago.zone/read-manga/a_proxy_painter/uu/ibx_chapter-20/pg-1/
But in Chapter 10 the doctor examining Ian says he is probably older than he looks because he was malnourished: http://www.mangago.zone/read-manga/a_proxy_painter/uu/ibx_chapter-10/pg-21/
So my guess is that Ian is in his early 20s? But he's the only character whose age is even hinted at so not sure about Raymond or the others.
Just curious,did anyone catch the ages of the characters?