IN THE MANGA they were married the 21 of november when Kotoko is 21 years old and Naoki too (remember his birthday is 12th of november so he is 21 years old too). IN THE DORAMA "It started with a kiss" they were 20 years old!! The Kotoko´s father said her mother was 17 years old when she was married with him so Kotoko who is 20 years old can marry too. IN THIS ANIME... I don´t know... but I guess they are 20-21 years old.

=]] i love this anime. sooo cute when she figfhts with her daughter... LMAO it's prob the reason why she hasn't aged much she still acts the same way she did when she was in highschool.