Osako converted Shinzo Koroki's pass inside the box in the 105th minute to claim the trophy for Kashima.

Kashima, who beat Urawa 2-0 the last time they won the competition, first threatened the Reds goal in the 25th minute when Takuya Nozawa forced Reds goalkeeper Norihiro Kato to punch out his shot and forward Koroki headed a Nozawa corner wide shortly after.

Oswaldo Oliveira's side enjoyed better possession in the opening period and came close again in the 37th minute when Yasushi Endo shot from the right side of the box.

Urawa suffered an early blow in the second half when Naoki Yamada received a second booking for a challenge on Takeshi Aoki and Kashima then created a couple of chances.

Koroki headed a Nozawa corner over the bar in the 57th minute and 13 minutes later Osako met Nozawa's free-kick with a header that went narrowly wide.

At the other end, Genki Haraguchi's attempt from a tight angle could not find the target before Kashima were reduced to 10 men with 10 minutes to go when centre-back Takeshi Aoki fouled Haraguchi and collected a second yellow card.

Kashima substitute Chikashi Masuda went close with his mid-range attempt shortly after the start of extra time while Urawa's Shunki Takahashi tried his luck from just outside the box.

Kashima finally broke the deadlock in the 105th minute when Osako met a Koroki pass in the area with his right foot to net the winner and came close to adding a second when midfielder Gaku Shibasaki hit the bar 10 minutes later.

"I'd like to congratulate our players. We've had so many things so far this season, which of course includes the East Japan earthquake on March 11," said Kashima boss Oliveira.

"But our players worked hard while keeping good discipline. This title is a reward for their hard work.

"I'm glad we have produced a good result like this and I am personally happy about winning the only title I did not have here in Japan."

Kashima will now face the winners of the Copa Sudamericana in the Suruga Bank Championship next summer.

"I'd like to congratulate Antlers. We went in to the game as a challenger but Antlers were a better side," said Urawa manager Takafumi Hori.

"It turned out to be a difficult game after we went down to 10 men but our players worked hard to the very end of the game."