For the longest time, anime has always been in 2D animation, which does make sense considering most animation studios are basing their animation off of manga images. However, with the advancement of technology, some studios have tried adding more CG animation in with 2D animation, or have tried making an anime entirely CG. This has lead to some success, but most of the time these project fail in some way or another. Mixing CG animation with 2D animation can cause an Uncanny Valley effect, as the anime can be 2D in one scene, CG the next, and then immediately go back to being 2D. This sort of mix can be extremely off putting most of the time, as these CG scenes are not always the best animated, or are extremely sort and are sprinkled in around 2D scenes. Animes that are entirely CG animated have had even less luck, thanks to infamous titles like Berserk, some anime fans are weary about any anime that is CG animated regardless of how good or bad the plot of the anime is.
However, I believe Houseki no Kuni is the chance CG animes have been looking for. The animation is amazing, and the transition between the small amount of 2D animated scenes and CG scenes is almost seamless, I was not even aware of that some scenes were 2D before someone mentioned it. The actual characters are gems, and their whole bodies are made of the gem they are suppose to represent, all the way down to their hair. This style of character is perfect for CG anime. It allows the animators to not have to worry about something looking too realistic or too cartoonish, another problem in some CG anime. Houseki no Kuni is able to use CG to its advantage, and was able to make a stunning anime with CG animation that looks natural.
Hopefully, other studios will follow take notes from Orange’s book and more well made CG animated shows will pop up in the future.