Devil_Hex
This chapter made me think about the Jashin fuinjutsu. I think its just seal imprint taken to the illogucal extreme. What I mean with that is that you make multipel interlinking(like how the 5 symbols seal works) juinjutsu seals and shrink those down to a level where they are barley visible(like what fujin expects happend to the blood guys seals) with those seals deciding what ability is granted(For example for blood guy there could be seals that harden and soften blood or move blood in diffrent directions) which would make sense since we have seen 3 diffrent special seal abilities(Blood guy,Ashina uzumaki, and Hidan) from which we cand deduce that the seals havent much to do with a persons innate talen but thier seal reserch(ergo somone who specilises in fire jutsu but only studies storage seals gets the ability to store things)
It would be nice if he tried to make more use of FuinJutsu during his combats. I don't remember seeing the (S)Iron Armor Seal. Is it similar to the Iron Skin Jutsu?? Maybe fujin could put some "Fire release" in the sole of his feet to make him even faster.... Or something similar. He could put a variation of the Training Seal in the enemy to make him heavier.... List goes on