Lady Lady!!

Both are basically an extremely (and even unnecessarily) dramatic "soap opera". In the 'drama' aspect, both are similar, the only difference being that Ie Naki Ko is an adventure. 

A blond kid gets to live in a castle in England with a noble family, but life there is not exactly rosy... If you have seen one of these series, you will recognize a lot of familiar elements in the characters, the story and the setting. However, the overall story is different, and other things are emphasized. So I think both of these little prince/princess stories can be enjoyed in their own right, even at this time and age... 

They both lost thier mothers too young, they have the same sweet fragile cute characters, Also having love complications. They're both a very intertaining and sad stories as well. If you enjoy one of them, you'll surly enjoy the other.