@Kizuro Yeah. Back on Earth his RL and game personalities were different. Now it seems difficult for him to use his game personality (Diablo, an Internet tough guy) and he's just the random, meek Japanese dude, who's envious of those succeeding in RL, but could never say it to them face to face. This has actually been consistent from the beginning of the manga. It's why he relies on the one-liners or not saying anything at all, leaving people to draw their own conclusions.
It doesn't really matter how good you are if you hesitate and don't do anything.