Switch Girl!! (2011)

These dramas both have Nishiuchi Mariya and it shows two completely different personalities by the same person. ( Even if it might not be the real person... if that makes sense.)

Both female leads only show their "beautiful face" to the world, but the ML sees them without their cover. Really similar themes of beauty with vs appearance.

Both dramas are about girls who seem normal, but are really slobs at home.

Same sense of fun and comic book over the top animations.

Both are comedies about girls hiding their "true" natures in order to fit in at school.

Same idea of hiding your "true" self in order to fit in at school; though in Otomen it is a boy who hides his "girly" likes, and in Switch Girl it is a girl who hids her "old man" behaviors.

This is the first season of the series and it will tell you the story of the main leads before they got to where they are now. Which will help you make sense of it all if you are looking to watch Switch Girl 2 which is picking up where the first season left off.

As far as over the top comedy and characters go, these two dorama are similar in taste. The stories are different, but they're both very funny.

sequel to the first drama and they both have the same female and male lead roles

both drama were adapted from Manga and they are both really funny. Both main character are really funny becasue of their unique personailty that make them stand out. They both are popular in school and have a good image in school becasue of their appearance but the truth was their real personality is nothing like their appearance.
For Switch Girl, Nika looks like a beautiful high school girl, but truth is she is actually like a hot blooded old man and acts very ungraceful and unladylike.
While in Yamada Taro Monogatari, Yaamada is believe to be a rich popular guy at school, but inrealtiy he is very poor and cheap over money and is a money grubber. He does not hide the fact that he is poor but becasue he goes to an elite school (on scholarship) and looks like a rich young master ppl believe he's rich and all.
Both drama is great comdey and keeps you laughing, though they are not all comedy bc there is a some romance for the watcher too.

Both cute goofy female leads who are attracted to a
"colder" male lead.

Both female leads are hilarious

In both dramas the lead characters are ridiculously dorky students who will do anything to win the heart of the person they love. Both dramas are incredibly funny and very strange.

Both stories are about a female lead with a secret double identity.

This is extremely similar plot wise to switch girl vise versa. Both shows have both leads living a secret life after school. In switch girl the main female lead is popular and beautiful in public, but at home she becomes her true self a gross mess . Her counterpart male lead is the exact opposite he goes from looking nerdy in public to being extremely handsome at home. He does this to avoid attention which is similar to Horimiya.