We've released the artbook for the game!
The artists did their best - it's a really awesome book, the only downside of which is that it's a digital edition. We advise you to read the novel before purchasing it - there are some spoilers ^_^
In addition, the OST for the game is now available in Steam (for free!).
Also thank you to everyone who bought the game and left reviews - thanks to you Ceiba is on the main Steam!