Dosei Mansion is a so far four volume science fiction manga by Hisae Iwaoka. It is unlicensed, but there is or was a live action adaptation movie in the works. You can find the author’s site and illustration gallery here. The latest announcement there is for the cover art of Apple Light’s Pocket of Rain album. Apple Light is a group that a lot like The Pillows, but more tame.

The basic story idea is of a young boy named Mitsu who lives in the lower and poorer area of a huge flying ring structure where people live. Mitsu graduates middle school, but his father dies and leaves him with the job of cleaning the flying ring’s windows. Humanity now lives in such places because everyone decided to no longer be allowed to step foot on Earth. The story takes its time and the artwork is flawless (see link above). Maybe there can be enough buzz or people bugging publishers to get the manga into English.

Apple Light – Pocket of Rain Amazon Japan
Volume one of Dosei Mansion Amazon Japan or beNippon