The actor's Tokyo-based family are all well and accounted for, but a lot of his friends are still trying to track down relatives following the disaster, which has so far claimed the lives of 2,800 people.
Oka admits he's "heartbroken" by the images of death and destruction he has been seeing on TV over the weekend as a desperate clean-up operation begins, and he may fly out to Japan this week (beg14Mar11) to see if there's anything he can do.
He tells U.S. news show Access Hollywood Live, "I was in Japan about a week and a half ago and I was actually supposed to go again this Wednesday, which I still might."
The actor reveals he was at a party with Japanese friends just before the tragedy struck: "I was ironically celebrating a birthday party with a lot of my Japanese friends... I came home, I was in a conference call with my colleagues in Japan (and) after I got off, my mum says, 'Watch the news...' I see all these images... It was really surreal...It's very overwhelming."
But he's very proud of his countrymen and women as they begin the process of piecing their lives back together.
He adds, "There's definitely a sense of community, a oneness with Japanese people and there's a lot of pride in trying to help each other as well as trying not to burden the people around you... They don't want to be a bother to other folks."
Oka is now urging fans to pray for Japan and give generously to the Red Cross - to boost the charity's relief efforts.
He states, "We're all connected as human beings and this is something that we have to work (on) together."