童心少女と大人世界 (Doushin Shoujo to Otona Sekai)

Background
This song is part of the Star Girl and The Illusion Paradise series by the doujin group, Story Researcher. It is the 5th created song but technically, the 3rd in the story sequence.

A song about a childish girl who is sick of growing up, wishes to forget the adult world and become a carefree child again. The city grants her wish and, after accessing the core of the city, she returns to being a kid. After a "shooting star" grants her and her friends wish to have something to play, she and her friends begin to use the junk received to build a paradise for the kids. They do this without realizing that they were repeating the system and world of the adults. In the end, while trying to return to her childish world, she ends up jumping into a sewer that was under construction. While in parallel, Rho and Lambda contemplate how the events unfold while commenting about them.

It is included in the official series compilation, Hoshi no Shoujo to Gensou Rakudo and also in EXIT TUNES PRESENTS GUMitive from Megpoid. This song has entered the Hall of Fame.