I've been playing "Rival Wings" on the JP data center, since it's active in my time zone!
Playing with the JP players is a completely different experience. Firstly, in NA, whenever the team is losing, people will usually express frustration in the chat, saying things like "Nice throw", "What a horrible team" or the infamous "...".
Other NA players are proud of how little they contribute or how badly they play, saying things like "I'm only here for the tomes". Once, a player was told not to shoot Oppressor missiles at players on foot, so he deliberately continued doing that for the entire match and said at the end "Sorry for using the Oppressor all the time". Sometimes, it can be risky to teach NA players, because there is a chance that someone will do the opposite of what you say to try and get a reaction out of you.
On the other hand, JP players do not complain or blame the team when we are losing. The chat will be silent unless someone is giving instructions, and any salt, QQ or finger pointing is rare. In fact, JP players sometimes say "Good game!" even when we lose. Even if they may privately feel frustrated, and are just obeying a social convention, I think they are being considerate by not damaging the mood further for other players.
This is never done in NA, if you gg after a loss, people think you are being sarcastic!
Secondly, in NA, people sometimes give explanations of game mechanics at the start. The mechanics of "Rival Wings" are complicated, so some people will explain the mechanics for newcomers.
On the other hand, JP players do not explain anything, unless you specifically ask them to. This is also true in DF (or as they call it, Content Finder, CF). The belief is that new players should be allowed to experience the content for the first time, and we should avoid spoiling it for them.
Despite this, JP newbies are on average more knowledgable about mechanics, and even most inexperienced players would collect CE and attack mammets. I guess that most of them read the game's instructions on how to play before entering, or are willing to learn on the fly.
NA players are more selfish. The veterans want others to read guides before they join, so that they don't have to teach; the newbies want veterans to teach, so that they don't have to read guides, and both sides try to minimize their own effort.
I really enjoyed playing with the JP players, even when I lost. Yes, even when I had to play against that really good Brute Justice pilot, who would Rocket Punch + Megabeam and KO me every time I tried to attack him, lol. I was sent back to the spawn point 6 times in a row trying to stop them from attacking the core, and got completely humiliated.
While JP players do not talk much in content, they are actually very friendly.
Today I had a very bad losing streak and was a little frustrated, so at the start of the next game, I used Google Translate to write in Japanese "I've lost 6 games today T.T". The Japanese players actually typed back encouraging things like "Let's give it our best shot!" in auto-translate and Japanese.
One cheeky person in my party typed "We'll definitely win with me around", haha. Unfortunately, we lost the battle at the start for the train platform. This player then typed "Sometimes we can't win even with me around", lol! Sadly, we didn't win that game, but I had a good time, so I don't mind!