If you liked the Glass Mask (2005) anime, the Anime-Planet community thinks you'd like:
Mari Wakatake is the sole survivor of an apparent island tsunami disaster that took place five years ago; she has been raised and schooled by her grandmother from that day. But now, she has been sent off to a boarding school in order to grow and make new relationships; and it is there that she meets Senkouji Hagino, a mysterious girl who is liked by everyone – everyone except for Mari. But Mari soon discovers that Hagino is not what she seems to be, and as Mari struggles to figure out Hagino and fit in at school, an alien race is maneuvering in the shadows for their conquest of an unsuspecting Earth. Little does Hagino know that she herself holds the key to the truth of Mari's past, as well as the key to her future.
Blue Drop and Glass Mask have a different premise, but the way the characters interact (the girls) give you the same feel. Blue Drop is science fiction while Glass Mask is all drama; this recommendation is based on the two having the same kind of "drama".
In Japan, one of the greatest idol singers of the time is the beautiful and talented Reika. Her three greatest followers are a varied bunch: religious Akari who loves to sing at her church, independent and self-sufficient Yuki, and the rich and snobby Nozomi. By chance, or possibly fate, the three finally meet at one of Reika's concerts, not knowing of the path they will soon be traveling together. With friendships and hardships in the future, can the girls manage to succeed on the path they will choose?
The teacher type figures were what struck me as being amazingly similar in Glass Mask and Chance Pop Session. In Glass Mask the main characters are trying to make it in acting while in Chance Pop Session they are focused on music but the teachers that help them out along the way take on the same type of persona. They are strict and ridged with the girls trying to make them succeed in the harsh world in which they endeavor to be in.
Chihaya Ayase is a famous beauty at her school, but she’s far from a conventional girl. Three years ago in her final year of elementary school, Chihaya and her friend Taichi became infatuated with the card game, Karuta, after connecting with a lonely boy named Arata Wataya. But when the trio graduated from elementary school, they each went their separate ways but shared one common goal: to excel in the game and meet each other at the national championships. Now, Chihaya is attempting to share her passion for the game by creating a competitive Karuta club at school, but when she reunites with Taichi it seems that maybe she’s the only one with the intention of fulfilling their childhood promise...
The average Tsukushi Makino attends the snobby, elite Eitoku Academy, which is dominated by the Flower Four (F4) – the sons of the most powerful families. Like the rest of her classmates, Tsukushi keeps a low profile until one day she can stand it no more! For her obstinance, the F4 declare war and it's Tsukushi against all. In the middle of it all, she finds herself drawn strangely close to two of the F4; they might not be as bad as they seem. With her heart torn between two boys, will Tsukushi be able to find the love she desires?
Both series talk about friendsheep and romance. We can find here a dramatic lovestory, where the hero is involved in a triangular situation. The main chacters can't understand their feelings in time or deny them till the end.
Asai Mugi's everyday life is very much impacted by a singular problem: she suffers from extreme shyness. Her sole friend Touyama Kayo would like to help her out as they've just entered high school, but Mugi's shyness is the sort that steals her voice entirely. It is too bad for Mugi that a freak shout on her part attracted the attention of Nono Ichinose. Nono is on a mission to save her Drama Research Society, and she isn't prepared to accept shyness as excuse from on-stage performances! With a small group of close friends to encourage and educate her, Mugi will be given a chance to be more than she is now. But, can someone so terribly shy really become a stage actress in just a few short months?
The style and even colour is different between Hitohira and Glass Mask, but both titles revolve around acting (or drama) as the story. You'll see some similar personalities in the characters, and the two anime have great OP/ED tracks.