What's the Kraang's connection with the Yokai?
I am unsure if the art book explains any of this, I still haven't been able to get my hands on it, so please let me know if any of this has already been explained.
I recently decided to rewatch ROTTMNT (the series), right after watching ROTTMNT the Movie for the first time. I did not realise this detail the first time, but it seems that both the Shredder and the Empyrean come from the Kraang, directly or indirectly. While the Empyrean's origin seems much more accidental (a crashed ship, seeping some kind of substance from within it), their association with the Shredder is quite intentional.
A little theory I have, is that the Kraang's involvement with Oroku Saki was an attempt at freeing themselves from the Prison Dimension. It seems they were imprisoned much earlier than the events in Karai's backstory, when she seals the Shredder. But that's not the main part that concerns me, but rather their relationship to the Yokai.
I feel it's fair to assume that the green ooze Baron Draxum uses in the first episode of the series is Empyrean, given the colour it has. It's also said that it is a substance that's quite central to the Yokai community, which makes me wonder, are all Yokai mutants in a sense? Probably not, since the series seems to want to lean into the direction of ancient magical arts. But this alien substance being so pivotal and fundamental to the Yokai community is rather curious, and perhaps it might have played a role in creating some of the Yokai.
Perhaps I'm just rambling a bit, but it's a detail I noticed and I am very curious about. As I said at the beginning, if the art book sheds some light on this situation I would really like to know about it, so please share your knowledge. And regardless of it, I would love to hear your thoughts and theories on this. It's a detail I find rather interesting.