Pink belly?

Yup! He ain't no yellow-belly!

It's like he's glowing from the inside!

My favourite part of this is the very-very smooth colours here, making his skin looks very pleasantly smooth. His yellow spines are also very cool-looking in a pleasant arrangement, though I can not say the same about the black spines around Shinji's jaw. I also notice how his expression and other body language give an 'inviting' feel.

The floor seems to 'warm' Shinji. However, the translation from the floor to the sky seems confusing, even with the flow of colours, possibly because the ground seems to just... stop. At least you have a sense of orchestrating the colours into an otherwise smooth transition. After all, even Shuinji's colours are reflected in the background. The one colour that Shinji has that the background does not is the green in the eyes, a colour that is otherwise missing in the transaction of the background. I like how you decided to include this 'missing' colour.

Wheew! Sorry for the super super late reply!
Thanks!
I did not want you to think that this comment went unappreciated, so better late than never!

As for the ground suddenly "ending" he is standing on an asteroid, but I guess I could have added more definition to the horizon line to give that effect.
And hehe. Can't just introduce a new colour without having it somewhere else in the image.