This is Sanguine in Lentus form (which seems to be his "emotional form", since he appears in Mr.  long-xiu's more emotional moments). He is nearly invincible in this forme.

Interestingly, though, he looks quite a bit like Woo Long from Build Tiger...

(You can only see this forme in deviantArt, though, unfortunately, at least until Mr.  long-xiu decides to upload a new drawing of him here...)

Sanguine Lentus -> Mr.  long-xiu