The historic victory has left Japan prime of Pool A with an ideal file after two video games, whereas Eire, so spectacular in beating Scotland final weekend, has suffered its first loss.
First half tries from Garry Ringrose and Rob Kearney, his effort transformed by Jack Carty, had left the Irish 12-9 forward on the half, with three penalties from Yu Tamura maintaining Japan in contact.
However the second half noticed Japan assume whole command with wave after wave of assaults, culminating in a attempt for substitute Kenki Fukuoka, transformed by Tamura.
Eire went into the World Cup because the No.1 ranked staff on the planet and coach Joe Schmidt was “extremely disillusioned that we did not handle to manage the top of the sport however they’re an amazing facet, they did very well,” he conceded.
His facet will look to get well in opposition to Russia in its subsequent sport, whereas Japan faces robust clashes in opposition to Samoa and Scotland in its bid to achieve the quarterfinals knockout stage.
For now, Japan coach Jamie Joseph may relish a victory that had been lengthy within the making, seen as an important conflict after the draw for the event was made.
“I am very pleased with the gamers, we clearly had a plan and we have fascinated about this sport for a very long time,” he stated.