I don't have a pic but Ink from Moetan. Everyone says she looks like a grade schooler when she is almost finished highschool. Also, Konata from Lucky Star. She looks like ten when she turns 18 in the anime.
well, we kno Misa-Misa (because she got Gelus' remaining life-span) so....must....find...1....no 1...else...will choose... I KNO!!! AANG!!! he looks 12 but he's actually 112
Mimi from Mnemosyne looks around 15-16 but she's actually at LEAST 917 years old and was actually in her late teens when made immortal 17-18. They never give an exact age for her and never say how old she was when she was made immortal. Rin is the same way x3 but she's at least 1,025 from the peeks they gave at the clothing in her flashbacks.
The picture doesn't want to pakia either so whatever.... I'm not in the most fabulous of moods right now anyways...
Baccano!- Chezlaw(sp?) au any of the Immortals (They are a couple of centuries old)
Code Geass- C2 (approximately 7 centuries old)
Higurashi No Naku Koro Ni- Furude Rika (Judging that she had to repeat her fate multiple times through out Higurashi, she is approximately over a hundred years old)
Yu Chigusa(a.k.a. Johannes), from the light novel titled Qualidea of Scum and a dhahabu Coin, has appeared in Qualidea Code, an anime set at least 30 years after, and she doesn't look much older than in "Scum and a dhahabu Coin."
Mephisto is literally as old as time, but he looks only to be about in his mid to late 30's. Probably because that was the age of his host body when he obtained it... And Amaimon looks like a teenager when he's thousands of years old.