Japan, bidding to reach their first ever quarter-final and carry the hopes of Asia, barely had a clearcut effort at goal in one of the worst matches of the tournament so far with Paraguay little better.
"I don't think I have anything left to do now, probably," Okada told a news conference when asked if he would now be leaving, although he said a definite decision would take time.
"It's my responsibility, we did not insist enough. I can not elaborate any further. When I look back at what I could have done for the players and what I did as a head coach I should have been more insistent on winning."
The match was drifting towards penalties as early as the middle of the second half but Okada was adamant he was going for the win, even if his side did not really up the tempo.
"All substitutions and changes I made were to try to push," said Okada, who boldly targeted a semi-final spot prior to the tournament but almost ended his second spell in charge after defeat in a World Cup warm-up against South Korea.
"It's difficult to narrow down why we couldn't score. We are not a team that can score lots of goals."
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