Don't worry about the age, she's not a real person. If she's drawn to look 25, then whatever age the author tells you she is is irrelevant...it just means you're attracted to adult women. Unless you're only attracted her because she's underage...which, yeah, is a problem, but it sounds like that doesn't apply to you.
I can't tell how many times I found a girl cute only for the author to pull out the old: "Oh she's actually a guy, ha ha got you!" Am I suddenly gay for being attracted to a female character design?
I'm not attracted to underage girls, that's disgusting! The only reason I thought she was an adult was because she had breasts and was shaking her ass in a skimpy dancing outfit.