This is my first critique, but I'll have a go at it.
First off, I love the overall idea. The character seems so serene, as if contemplating every fleeting thought. I'd say that the shading and detail work are well done - it's as if every strand of fur was really drawn in there. Great work on that!
However, I'm a bit confused on those blue flame-things (I lack better words). Do they provide a light source? The one on the right looks as if it is; there seems to be light glinting off of the character's lower paws, especially the left leg. The one on the left, though, looks like it's just glowing without any of the light bouncing off of anything else. There does seem to be light on the character from this side, but it appears more as if the light is coming from the back of the character instead of the side. Perhaps try having a little bit of light glint off of the face of the character? It does seem to be facing toward the 'flame'.
Other than the questionable lighting, I think you have done a very good job and this and deserve the praise it receives. Keep up the good work.
Koto - this piece is amazing, but I believe Dark Madness is still my very favorite piece that you have done. They both have very different ideas.
I'm impressed by your highlighting technique first of all. You've done a good job at lighting up the wolf's fur around where a "soul" is. I also really love the organic shapes of the souls. Personally, I would like to see more light illuminated around the souls, and possibly a trail following behind them, or some other method to enhance a type of "movement" (unless you were attempting to have them in still motion). This is all personal taste, and you are entitled to your own opinion. It's not to degrade this lovely piece of work at all, I hope you know that.
Well you know me and you know I love fluffy tails, which the subject has, and it is gorgeous! It is looking a bit on the foxy side, but if you meant to do that it's totally fine (I do it all the time). There is one piece of advice for you that I have. The bottom of the tail is nearly touching the bottom of the border of the picture, which is creating a tangent. A tangent causes unnecessary tension to the viewer (is it touching or isn't it?) so I would suggest either having the tail noticeably hanging off the picture, or not having it so close to the edge (or perhaps darken more of the tail to give the impression that it is lost in the darkness).
The expression is great. To me it gives a feeling of deep reflectivness and a little bit of a slow struggle.
Great job Koto. I love seeing these works from you! Please don't take my comments to personally. They are only meant for improvement