The 30-year-old Celtic midfielder has been putting in overtime curling free kicks over and around a plastic wall in preparation for Saturday's showdown in Saitama.
"I've got them just about right," Nakamura told Friday's Japanese media. "I'm getting the ball up and over the wall nicely -- it's nice to know you have that weapon."
Japan can seize top spot in Group One, at least for a few days, in the final round of Asian 2010 qualifiers if they beat a stubborn Bahrain team who have frustrated them in recent games.
The Gulf side have beaten Japan in two of their last four meetings and another slip-up by the home side will increase the pressure on under-fire Japanese coach Takeshi Okada.
Nakamura, who has recovered from a niggling groin strain, hopes to cash in should Bahrain's defenders dive in and commit fouls on the edge of their penalty area on Saturday.
"We have the quality," said Nakamura, one of the few among Japan's players and coaching staff to escape criticism in a stuttering World Cup qualifying campaign.
"Japan have the ability to play quick, one-touch passes to create space to shoot but we have to take more risks near their box to break them down."
Australia, who held Japan to a 0-0 draw in Yokohama last month to preserve their two-point lead at the top of the group, face Uzbekistan at home on Wednesday.
The Socceroos have won three matches and drawn one while Japan have won two and drawn two. The top two from each of the two groups qualify for the 2010 World Cup in South Africa.
Bahrain are third in Group One with four points from four games, ahead of Qatar on goal difference.
The winners of a playoff between the two third-placed teams take on Oceania champions New Zealand for the final place in the 32-team tournament.
