If you liked
GTO
|
...then you might like
Rokudenashi Blues
|
I'd say the main characters really resemble each-other quite a bit. And they're both in a school setting revolving around delinquents. They're both tough guys, who're really very stupid, but always have their eyes set on doing what's right. Being nosy and involving themselves when they see something's not right. I'd say they're remarkably similar.
If you liked
GTO
|
...then you might like
Fly-High!
|
Probably not for the same age groups. But the concepts of each are relatively the same. In that a new person at school is put at odds against a group of students, merely for taking up a position of power. But the protagonist of both manage to turn the hearts of those against them.
If you liked
Yu☆Gi☆Oh!
|
...then you might like
Othello.
|
Both are about a weak person in High School, who happen to have split Personalities, that take up the role of "Punishing" those who bully the alter ego. Though Othello is also a romance, and a bit more serious.
If you liked
One Piece
|
...then you might like
Dollgun
|
Both about Treasure! The quest for a Treasure left behind by the most famous of Thieves/Pirates.
If you liked
Koukou Debut
|
...then you might like
Kyou, Koi wo Hajimemasu
|
Both have an unpopular girl who is looking for love in High School. And they meet a popular boy who isn't interested in love. Because of some similar event they end up hanging out without eachother where love develops between them.
If you liked
Kaichou wa Maid-sama!
|
...then you might like
Kimi ni Todoke
|
They both involve a high school relationship, and in both, they all have trouble understanding eachother's feelings, even though it's quite obvious that they are in love. And this leads to a few misunderstandings between the parties because they have problems conveying their feelings properly. That's all the real similarity between the two. In terms of plot setting. Other than that, they are quite different.
If you liked
Ichigo Mashimaro
|
...then you might like
K-On!
|
K-On really seems like it's Ichigo Mashimaro in High School. As for the episodes. While there is no definitive plot in either of them. There is a sequence that they follow, and they don't keep things random. 4 girls who hang out, and have a great time, all the time. As well as a 5th, older girl who likes to dress them up as Cosplay. That's the main theme that they share. Though the actually theme of each would be a bit different (^.^)
If you liked
Onegai☆Twins
|
...then you might like
W: Wish
|
A Brother and 2 sisters. But only one can be his sister. They are essentially similar stories. Bother revolve around the Supernatural to an extent. And carry similar themes.