The 22-year-old Barcelona forward was a class apart at Singapore’s national stadium as he scored all of Brazil’s goals and nearly provided more in front of a sell-out crowd.
Neymar underlined his star billing as he moved to 40 goals in just 58 games for Brazil and gave new coach Dunga a fourth straight win with no goals conceded.
The victory also rounded off a successful Asian mini-tour for this year’s World Cup hosts after Saturday’s convincing 2-0 win over arch-rivals Argentina in Beijing.
Neymar looked dangerous from the off. In an ominous start, he had a penalty shout waved away and grazed the side-netting with a free-kick.
He duly put Brazil ahead on 18 minutes when he ran on to Diego Tardelli’s penetrating through-ball, scampered around goalkeeper Eiji Kawashima and finished with aplomb.
Neymar pierced the Japanese defence once again when he evaded the attentions of Tsukasa Shiotani on the left and went close with a shot which rolled across the goalface.
But Japan were not prepared to roll over and Yu Kobayashi flashed a volley over the crossbar as the Blue Samurai nearly found a quick reply.
Bundesliga’s Shinji Okazaki almost found the target with a glancing header and Brazil dealt poorly with a corner on the stroke of half-time in signs of hope for Japan.
But Japanese optimism receded three minutes after the break when half-time substitute Philippe Coutinho won possession in midfield and prodded the ball forward for Neymar.
With Japan’s offside trap sprung, Neymar had plenty of time to pick his spot and put his second goal of the night past Kawashima.
Okazaki, now bolstered by substitute Keisuke Honda, remained industrious and made the Brazilian woodwork shudder with a fierce shot that cannoned off the near post.
Neymar should have have sealed his hat-trick when he rounded a defender and shot with the goal at his mercy, only to see the side-netting bulge.
The 22-year-old was tormenting the defence and he set up first Liverpool’s Coutinho and then 65th-minute substitute Robinho for carbon-copy chances on the left which both went wide.
Kaka arrived to huge applause in the 72nd minute and he quickly drew the best from Kawashima as his firm header, from a Neymar cross, was palmed onto the bar.
But the ball was not cleared and although Kawashima kept out Coutinho’s fierce drive, Neymar pounced on the rebound for his third on 77 minutes.
Four minutes later and Neymar got his fourth of the night, and 40th in a Brazil shirt, when he met Kaka’s hanging cross from the left at the far post.
Substitute Yoichiro Kakitani nearly grabbed a late consolation for Japan. But there was to be no fillip as the Blue Samurai look ahead to their Asian Cup defence in January.