Aki isn’t a brave little boy, but he’s dedicated nonetheless to safeguarding his sickly, mute friend Fuyu. They and their little gang live deep underground, in the concrete warrens to which survivors have fled following the eruption of Mt. Fuji. The community is in decline, however, as illness and despair take their toll. Fuyu dreams of the outside world, which he is too frail to ever reach. But what colour is the sky out there?
| Directing | Toshihisa Yokoshima | Director |
| Art | Kouji Hashiguchi | Concept Artist |
| Art | Mitsuji Kamata | Art Designer |
| Production | Junpei Mizusaki | Producer |
| Production | Ittatsu Shimizu | Producer |
| Camera | Manabu Kadouno | Director of Photography |
| Visual Effects | Michi Suzuki | Character Designer |
| Art | Kouji Hashiguchi | Background Designer |
| Art | Yuichi Suehiro | Art Direction |
| Sound | Ryuudai Abe | Music Director |
| Sound | Ryosuke Naya | Sound Director |
| Sound | Kaoru/Brilliance | Music |
| Writing | Toshihisa Yokoshima | Screenplay |
| Art | Toshihisa Yokoshima | Storyboard Artist |
| Sound | Hiroki Nozaki | Sound Effects |
| Editing | Kiyoshi Hirose | Editor |
| Visual Effects | Yoshihiko Ishiguro | CGI Director |
| Art | Shiori Iwahara | Background Designer |
| Art | Katsu Nozaki | Background Designer |
| Art | Yuichi Suehiro | Background Designer |
| Art | Yoshihiro Sono | Background Designer |
