possibly the work of Atsushi Yamagata but I'm not sure if a presumed tag is worth it.

aside the neat animation of the action part per se, I find that brief cut with the scene mirrored in Leorio's glasses while he adjusts them quite stylish and inventive! Also I noticed just now Canaria's hair movement before she delivers the hit, it's a clever trick to build up kinetic tension (and could maybe foreshadow Nen-related stuffs? I dunno.). Also that thing reminds me when Ghibli characters get angry and their hair slightly sort of... move? puffs up? I imagine everybody knows what I mean :P

there are alot of scenes that needs to be added for HxH 99

and I still think 00;:6 to 00:20 is NC norio