In the 11th minute Kirsten Pearce slotted the ball into the net and the Kiwis celebrated but the umpires, Mary Driscoll (USA) and Liu Xiaoying (China), deliberated before disallowing it and awarding Japan a restart on the quarter mark for what appeared to be a foot fault in the scramble from a pile driver of a shot from outside that Kageyama had padded away.
A minute before the quarter ended, the hosts had a PC opportunity but were unable to find the target.
Umpire Liu flashed a green card at Tessa Jopp for a two-minute spell in the naughty chair for stalling play in the 19th minute.
The second quarter reflected a lot of endeavour but the only penalty corner came for the Black Sticks with a minute to go. However, Kageyama and her backline were on the beat to thwart sweeper Brooke Neal's strike from the top of the D as the hosts went into halftime maintaining their lead.
The game came to a halt for about eight minutes into the third quarter after a Japan defender went down clutching her calf after a spirited attack from New Zealand.
A stretcher was brought out, enabling both sides to revisit their game plans in huddles on the turf, and medics later wheeled her off with an ice pack wrapped around the calf before play resumed.
The quarter ended scoreless with Japan again content on sitting back.
It wasn't until the 49th minute, after New Zealand missed a PC, that Japan counterattacked and almost levelled the score but the experience of Sally Rutherford came to the fore.
The Rutherford spectre rose again in the face of another Japan attack in the 53rd minute to keep the tourists at bay. She backed that up immediately when she thwarted a failed PC attempt as New Zealand threatened to increase the lead. Pearce ran down the right flank, crossed to midfielder Pippa Hayward who, unfortunately, couldn't deposit the ball into the goal.
With four minutes to go, Rose Keddell had inscripted Japan's epitaph with a reverse stick shot from the top inside of the D to increase the lead, 2-0.
The opposition had no one to blame but themselves as some lacklustre air shots left the ball dangling to be rifled in.
Before the stunned and emotionally drained Japan could regather, Merry drove a stake into their heart within seconds of the restart for a 3-0 gulf.
Returning veteran Samantha Harrison had another chance with a minute to go but couldn't finish it as the delighted crowd counted down the seconds - but not before Rutherford made another save at the other end.