If you liked the Ouran High School Host Club anime, the Anime-Planet community thinks you'd like:
Sousuke Sagara is far from the average high school student - not only is he highly trained in military tactics, he puts his knowledge to use in every single applicable situation (and even those nonapplicable ones.) So, when confronted with high school, he tends to turn average high school experiences into off-the-wall adventures. Love letters become terrorist threats and field trips become commando operations; his survival depends on the watchful eye of his best friend and classmate, Kaname. Together, they may just make it out of high school alive...
Although Ouran parodies shoujo anime and Fumoffu is focused more on parodying action films, both series have a similar mix of romantic comedy and parody. Both also have really fun, memorable, enjoyable characters. It should probably be noted for fans of Ouran that Fumoffu's comedy is sometimes raunchier, and fans of Fumoffu should know that Ouran places a greater emphasis on the romance element of the show than Fumoffu ever does, but overall I think fans of one should give the other a chance.
I could just say school antics and leave it at that, but there are some other similarities between the two. Like the male lead seeming to be out of touch with reality half the time, and the female lead desperately trying to talk him down (and failing). And the romance between the protagonists never really develops, despite attempts by the side characters.
Ever since they met, emotionless Hotaru and ditzy Mikanhave been best friends, and are virtually inseparable-- that is, until Hotaru is invited to attend a strange school far away, a school for those who have special abilities known as "Alice". Unable to be separated from her friend, Mikan soon sets out on a mission to find her. After traveling to a city far away, she finds Hotaru at last, but gets much more than she bargained for. Now, she is lost in a school full of kids with strange powers, unusual animals, and has secured an immediate rivalry with the toughest little punk in town!
Both series have a theme of "low class but cheerful girl" entering rotten world of rich/talented and saving every1 around her without even realizing that.
Although this recommendation is more apt towards the manga, which is definitely deeper and explores more content, is can still apply to the anime. Both, at first glance seem to mostly potray a comic and cutesy type shoujo with some sweet moments and romance here and there. It's funny but it's the humour that actually shades off just how deep, dark and complicated some relationships, characters and plots actually are. They both will always remain among my top 5 favourite series.
As a member of a musical duo on the verge of making it into show business, Shindou Shuichi has a lot on his mind -- especially since he writes the songs for his Bad Luck band. His life gets no less hectic when he bumps into Yuki Eiri, a successful yet cynical author extraordinaire, who immediately insults Shuichi’s lyrics upon reading them. Seeking him out to demand an apology, Shuichi nevertheless sees other facets of Eiri’s personality. Can he accept the fact that he might be developing feelings for the novelist who discredited his work on their first meeting?
Both Ouran and Gravitation have the same blend of slapstick humour with the occasional serious moment thrown in. The artwork is stylistically similar, and the humour is just as random and eccentric.
Simply for comedy reasons both of these anime must be watched. The ridiculous sense of humour found in both of them is also couped by occassional moments of angst and dark backgrounds to most of the characters. While Gravitation is solid shounen-ai, Ouran isn't, but while saying that all the characters are highly slashable and while watching either of them you'll find yourself echoing the ouran girls' 'KYA!'
With a history of leading a motorcycle gang and getting bad grades in school, why would 22 year old Onizuka ever want to become a teacher? Is it to educate young minds or spread the joy of education? Sure, if it involves being able to look up high school girls' skirts! Watch as this would-be educator uses his own life lessons and unconstituted methods as a means to control a delinquent class of students -- students who certainly aren't as happy to have him as a teacher as he is happy to be teaching...
Its not quite the same settin, nor feeling, but I think these series have something in common which would do that you like both. It's how they both (patially) describe japaneese school and everyday life, with a storyline with romance and a large dose of humor.
Both animes have a similar school life feel to them with humorous and sometimes ridiculous occurences happening to the group of main characters. The episodic style is also a common theme between both of these two fantastic anime. GTO's humor is slightly more vulgar in its nature, but not ridiculously so.
There are a whole group of boys around the cross-dressing female lead in both of these series and there is a variety of personalties among the group. Also, both lead girls seem similar to me, in that they are neither a tom-boy nor very feminine, not strong but not the weak, crying type.
The similarities between Hakuouki and Ouran are not in plot.I think they're similar in the characters: a bunch of handsome, overprotective, guys and female cross-dresser.
In short, if you like/liked one you'll probably like the other.