Star Girl and The Illusion Paradise

The Girl's Fantasy Cinema (少女の幻想劇場) is a series by Story Researcher (doujin group formed by cosMo and GAiA). CosMo is in charge of the music and illustration, while GAiA collaborated with him in the lyrics.

Currently this series is still in progress.

Background
This series seems to be the possible (unconfirmed, however heavily hinted) sequel to The Fantastic Garden (空想庭園) series.

The story occurs in a strange city that grants the wishes of the girls who live there. Though they get what they want, the question is if will it really make them happy and how long will they try to run away from the truth. While this occurs, a mysterious and obscure character tries to make them all realize the truth using harsh techniques.

家出少年と迷子少女 (The Runaway Boy and Lost Girl)
Sung by GUMI

In this song, GUMI (Lost Girl) is upset because the boy she was in love with "ran away," so she searches all over an unfamiliar town to look for him. Once she reaches the railroad crossing, however, she remembers the truth: the boy died. She then stands on the train tracks, and (possibly?) commits suicide, not wanting to live without him.
 * Nicovideo Broadcast
 * Youtube Broadcast (with Subtitles)

修道少女と偶像少女」 (The Nun and Idol Girl)
Sung by Hatsune Miku
 * Nicovideo Broadcast
 * Youtube Broadcast (with Subtitles)

This song is about a girl who enters the religious life as a nun. She listens to the confessions of the citizens, but really doesn't understand what her job is, nor does she take it seriously. She is bored with her life and wants to make it exciting, so, by the advice of her computer guide, she becomes an internet idol. When fans begin to turn against her, she threatens to do something about it with a knife - only she begins to remember that she was an internet idol once before, and had been cutting her wrists in response to fan negativity. She returns to the church and is about to cut her wrists, but is stopped by a young priest and accidentally stabs him. Unable to do anything, she vows to return to her life as a nun and continue apologizing to God for her crimes.

Dr.リアリスト (Dr. Realist)
Sung by Kamui Gakupo, backup by Kagamine Rin & Megurine Luka "You all have no interest in 'reality', do you?". We are introduced to Dr. Realist and his girls (assistants?) Rho and Lambda, the two from ANTI THE∞HOLiC. Dr. Realist is a strange gentleman who despises the people within the city for not facing reality and escaping into the city's illusions.
 * Nicovideo Broadcast
 * Youtube Broadcast (with Subtitles)

迷子少女と流星紳士 (The Lost Girl and the Meteor Gentleman)
Narrated by GUMI and Kamui Gakupo Instead of a song, this is a brief dialogue. During Runaway Boy and The Lost Girl, Lost Girl meets Dr. Realist. He decides to help her look for what she "lost", and leads her to a train railway.
 * Nicovideo Broadcast
 * Youtube Broadcast (with Subtitles)

童心少女と大人世界 (The Childish Girl and the Grown-Up World)
Sung by Gumi with Kamui Gakupo, Kagamine Rin and Megurine Luka A kiddish girl who is sick of growing up wishes to forget the adult world and become a carefree child again.
 * Youtube Broadcast (PV-less yet, only available on the GUMitive album)

ルカリンオリジナルコース 「Infinite∞HOLiC」

 * Nicovideo Broadcast
 * Youtube Brodacast

Trivia

 * The song Runaway Boy and Lost Girl contains multiple references to cosMo's The Fantastic Garden series:
 * There is a traffic light with "Atelestia" written on it (from In the Ruined City Atelestia). Later, on Lost Girl's second run, Rin and Len show up looking the same as in the video
 * Shii-tan (the girl from Θ Capsule) watches some fish fly, and jumps off a building. Also, the very next building has the word THETA (θ) and CAPSULE written on it in English
 * A route sign '18' and the girl on a bicycle show up from R-18 (though it is not tagged as one of the songs in the series)
 * A radio tower and some radio waves are pointed out, from The Girl's Fantastic Garden. Later, on the second run, Feather Pen Girl appears on some buildings with flowers from the Fantastic Garden
 * Dr. Realist's monocled star avatar shows up in a few videos in (and outside of) this series, including:
 * Θ Capsule in the background to the right of Shii-tan
 * The Runaway Boy and Lost Girl, on her second run through the city, the Star blocks the hole leading to the Inner City, letting her reach the train tracks
 * Nun and Idol Girl, as Miku's computer guide
 * One of the original tags for this series was "街＜ステラ＞シリーズ"or "街《ステラ》シリーズ" ( City Series), but was changed shortly after the upload of Dr. Realist. (Youtube uploads that used this tag can be found here.)