Henao941 said:
Are there any Japanese animators who make animation tutorials or have done blogs talking about how to animate? Also, are there any animation books that where written by famous Japanese animators?
I think books are obsolete. You can't pick up the psychology of an artist on how to draw, it's better to watch impromptu videos. And most books are all about feel and copy.

I found a very extremely technical technical tutorial but's it's in Japanese. You can use Chrome Extension - "CopyFish OCR" to understand the video. This person works in anime studio named "Wix Studio" that did Attack of Titan. https://www.youtube.com/channel/UCiT0Di_03OKokFYYb0u5dlw

On the Video you have to watch how the frames and keyframes are setup, it's more than what the animator is commenting. Like how the color frames are color to identify be key frames and in-betweens and setting up the tools to make them.