Okubo was sent off during last weekend's 1-1 draw in Oman after lashing out at kicking goalkeeper Ali Al Habsi, earning him a verbal volley from Japan coach Takeshi Okada.
The former Real Mallorca forward made a tearful apology to Okada and Japanese officials but was still forced to travel with the team to Bangkok despite his subsequent suspension.
While Okada labelled Okubo an "idiot" for his moment of madness, the Japan players have refused to blame their team mate, whose short fuse has landed him in trouble in the past.
"He's not a bad boy," central defender Tulio told Tuesday's Japanese media. "He's not fighting for himself, he's fighting for the team."
Midfielder Yasuhito Endo also leapt to the defence of Okubo.
"Yoshito plays the game hard," said Endo. "We're not that upset about it. At international level you have to play the game as close to the edge as you can."