Japan dominated from the outset, taking the lead in the sixth minute when a low shot from Fuka Nagano was directed into the bottom corner by Tanaka.
Tanaka doubled the lead in the 32nd minute when Hikaru Kitagawa crossed from the left and the Japan striker took advantage of hesitant Australia defending to sneak and slide the ball home.
Japan's third goal was a showcase of their clever, short-passing style, ending with Tanaka slipping the ball across the goal to Maika Hamano who slotted home.
Australia were simply never in the contest at Shell Energy Stadium with interim head coach Tom Sermanni's side second-best in all areas.
Tanaka missed a great chance for her hat-trick but fired over from close range but Japan soon had their fourth when from a short corner, Kitagawa floated in a cross and Moeka Minami glanced in a header.
Australia's best effort came in the 87th minute when substitute Charlotte Grant hit the bar.