Okada revealed his decision not to include the former Eintracht Frankfurt forward after team training on Thursday.

"I spoke to him the day before yesterday, and he was not happy with his current conditions and I am not happy either," Okada said.

"I thought it would be better for him to return to his club to regain his form, as he won't have as much training with us as he would with them.

"But I'm sure we will require him later. That's why I put him in our squad and hope that he can come back soon."

Takahara has scored only two goals in 11 matches for Urawa this season and has yet to find the net for his country in four appearances

The 28-year-old forward did not show up at the team hotel in Yokohama on Thursday when the rest of the squad got together.

No replacement has been called up to take his spot.

Japan are currently second in Group Two in the Asian World Cup qualifiers with three points and face Oman in Yokohama on June 2 at home before visiting the Gulf side on June 7 in Muscat.

They then play Thailand on June 14 in Bangkok before completing this stage of the qualifiers with a home match against Bahrain on June 22 in Saitama.

The top two sides in the group will advance to the final round of the World Cup qualifiers.