I think it only analyzes recent entries, because mine had Fruits Basket characters on the list, but nothing having to do with Harry Potter, and I'm certain that in the entire course of time I've kept my journal, I've mentioned Harry, Ron, and Hermione, way more often than I've mentioned Kyo, Tohru, and Yuki. So perhaps you've been mentioning Tohru more recently?

Just for fun, I analyzed fruits_basket. Only four charcters names were on the top 100 list, and I bet you can't guess who was the first, at slot number 25. The other three were Tohru at 47, Shigure at 69, and Yuki at 99. Kyo wasn't on the list at all. :( Makes me want to make a post there about how wonderful Kyo is, and use his name 20 times. Heh. Maybe it's just because his name is spelled two different ways.