If my work's going to be compared to Enigmo (as if he's a high standard to begin with) then I know that I am wasting my time and other people who are reading this thread's time.
Anyway, here is my previous image, but this time I painstakingly went back and removed just a hint of blue, and here. No color cast at all.

To the naked eye the difference is almost imperceptible, but in fact, it is changed:

There.
(and before you complain that it's not completely greyscale, you should know that the grain on the Dragon Box has slight color variation throughout the entire image. You can see this when you zoom in closely. It is impossible, without manually adjusting the color of everything in the frame for every single frame of the 18 minute per episode, 291 episode series, to change, so it wouldn't ever be completely grayscale in a legitimate color correction)