Having scored a meagre four touchdowns in the first Test, two periods of early dominance in each half paid dividends for the Irish in soaring temperatures at the tightly-packed Prince Chichibu Memorial ground.

Munster team-mates David Wallace and Frankie Sheahan bulldozed their way through for Irelands openers inside the first eight minutes.

Two turnover tries for Japans record try-scorer Daisuke Ohata either side of the interval kept the home side interested, but five Irish efforts in the third quarter, including two for Harlequins ace Gavin Duffy and Sheahans second, sealed an eighth win of a 10-game season for the tourists.

Strong running from Munster wing Anthony Horgan sent Wallace, playing alongside Denis Leamy and Eric Miller in the back row, over for Irelands first score on three minutes.

Fly-half and captain David Humphreys converted - to leapfrog Ronan OGaras Irish points-scoring record of 525 - and added the extras to Sheahans second try of the tour, set up by a clever inside pass from Peter Stringer five minutes later.

Japan, with former New Zealand Maori flanker Hare Makiri and ex-Otago centre Reuben Parkinson to the fore, began to make inroads into the Irish defence and they deservedly closed up the deficit to 14-10 by the interval.

Returning number 10 Keiji Hirose banged over a 32nd-minute penalty before lighting wing Ohata sprinted 50 metres from an Irish turnover to score.

Three tries in the opening nine minutes of the second half from ODonovans visitors put paid to any hopes the Cherry Blossoms had of an upset.

Humphreys notched the first two minutes in, after a neat break by Millers replacement Alan Quinlan. Duffy added Irelands fourth 50 seconds later from turnover ball and Tommy Bowe set up full-back Girvan Dempsey for another on 49 minutes.

Duffy added his second - his third try in four Tests - eight minutes later for a 40-13 buffer, with the score crafted well off an Irish lineout on halfway.

Speedster Ohata then claimed his second of the afternoon - and incredibly his 46th try in 46 Tests - when making the most of a Parkinson pass out a tackle.

Ireland had the final say on 66 minutes. With players wilting in the heat, hooker Sheahan dived over for his second following a close-in drive.