Well, the version is different.
Last patch from Nexon broke many things (inability to use ground-targeted and party-targeted skills, ability to run after casting Flame Breath/Rubric, which also had a very long duration). One month later Nexon made an announcement about the service termination.
Then IMC took over JP version and recycled the client.
I mean, I saw this link to nexon.co.jp in Steam client which was funny.
IMC reverted a few patches to the point where my Wugushi had problems with flying enemies again.
jTOS had Arts update on January 8th and no 4Ever update so far (2 weeks behind iTOS).
All in all, jTOS client is in a very messy state right now. Maybe it will improve later.