The new Barcelona acquisition turned in a superb display to inspire the Selecao to three points and keep their hopes alive for a third consecutive Confederations Cup title
Goals from Neymar, Paulinho and Jo ensured the Selecao maintained their unbeaten record against the Asian champions with a convincing performance to alleviate some of the pressure on Luiz Felipe Scolari's shoulders.
Brazil's performances had come under scrutiny since the re-appointment of Scolari but they appeared solid at the back and irresistable in attack, throwing down the gauntlet to the rest of the world that they are serious contenders for the World Cup next summer.
There had been much debate as to whether new Barcelona signing Neymar could rise to the occasion and he provided the hosts with the dream start with a sumptuous strike after just three minutes.
The 21-year-old ended his nine-game streak without a goal for club and country with a stunning half-volley into the top right corner after Marcelo's cross had been deftly cushioned into his path by the chest of Fred.
Japan almost struck back immediately when Keisuke Honda tried his luck from distance but his fierce free kick was palmed to safety by Julio Cesar.
The CSKA Moscow midfielder proved a constant thorn in the Selecao side and he forced the QPR shot-stopper into another save on 18 minutes from the edge of the box after jinking inside the challenge of David Luiz.
The partnership of Dani Alves and Hulk down the right wing was causing the Japanese defence problems and the pair combined excellently on 22 minutes, but the Zenit forward's dangerous low cross was crucially hooked clear by Japan captain Makoto Hasebe.
The same two players combined again five minutes before the break with Alves feeding Hulk on the right-hand side of the box. The forward cut inside the challenge of Yuto Nagatomo onto his preferred left foot before thumping a ferocious drive into the side netting with Eiji Kawashima scrambling.
The Samurai Blue came out of the blocks quickly after the interval but it was the hosts who doubled their advantage three minutes into the second half.
The relentless Alves drove forward from defence before his fizzing low cross was controlled expertly by Paulinho, whose low shot somehow squirmed under the body of Kawashima.
Alberto Zaccheroni's side really should have pulled a goal back on 50 minutes when Hiroshi Kiyotake's teasing low cross found Shinji Okazaki in the area, but the Stuttgart forward inexplicably steered his effort the wrong side of the post.
Ryoichi Maeda was introduced in a bid to add some attacking steel to Japan's play and the striker nearly reduced the deficit on 72 minutes when he latched onto a loose ball in the Brazil box before swivelling and forcing Cesar into a smart stop with his low effort.
The boos did ring out for Scolari, however, when he opted to withdraw Neymar from the action, but with games against Italy and Mexico to come, the 64-year-old's decision was understandable.
Late substitute Jo added gloss to the scoreline in stoppage time when he swept home from Oscar's pass after a devastating counter-attack to cap a wonderful display from Scolari's side.
Brazil could secure progress to the semi-finals with victory against Mexico on Wednesday whilst Japan look to get their first points on the board when they face Italy.