"We felt today we out-passed Japan, we kept the ball better than them, we looked more comfortable in possession and they found it a lot harder to break us down than we did to break them down.
"As much as there is a despondent mood, because we know we played better than the result suggests, people are happy and they know it's been a good performance and one we can really leverage off."
Having had the better of the game up until the goal, Readings said the manner they conceded it serves as a timely reminder of how important the little details could be in Canada.
"I think you could pinpoint things on that corner we could have done better but there's a whole heap of things that could have been done one percent better across the pitch multiple times which would have made a big difference."
Readings said the Wilkinson penalty proved a decisive moment in the game which could have produced more for the New Zealand side in several ways.
"When the penalty was awarded we were surprised there wasn't further action in terms of a yellow or red card. As the last player, a red card at that point changes the complexion of the game completely with us right on top at that moment.
"But we can't control those aspects of the game so I'm happy with the way we stayed focussed and continued to threaten Japan through our approach."
In the early stages of Sunday's match, the Football Ferns enjoyed more possession than the home side and crafted the first sight of goal 11 minutes into the contest.
A neat exchange between Sarah Gregorius and Annalie Longo released the Coastal Spirit midfielder into the Japan area but, under pressure from the recovering defenders, Longo's shot was hit straight at goalkeeper Erina Yamane.
The tight contest continued to see both sides unable to craft regular openings and it was a set piece which saw Japan take the lead just after the 20 minute mark.
Having earned a corner, the ball was swung in where Sawa arrived ahead of her marker to volley in from six yards to give her side the lead arguably against the run of play.
The home side stepped up their work after taking the lead, creating several good crossing opportunities before the break but each one saw the ball evade the on-rushing Japanese support and the Ferns survived.
Quality scoring chances were also rare at the other end, a blocked Betsy Hassett shot the best of the efforts the Football Ferns had on goal before the split.
Moments after the restart the New Zealand side had a golden opportunity to get back on level terms.
Wilkinson broke in behind to collect a through ball and was tugged back and the referee pointed to the penalty spot. Picking herself up to take the spot kick, the University of Tennessee striker blazed the ball just over the Japan cross bar.
The defending FIFA Women's World Cup champions survived another scare on the hour mark as Ria Percival swung in a free kick from deep.
Captain Abby Erceg contested the falling ball and it dropped to Amber Hearn who headed towards an unguarded net before it was hooked clear off the line.
That chance proved to be the best sight of goal for either side in an increasingly open affair through midfield but neither team could find the required moment of quality in the final third to add to Sawa's strike.
New Zealand now move on to Canada later in the week to begin preparations for the June 7 (NZ time) FIFA Women's World Cup opener against the Netherlands.
Japan 1-0 New Zealand (half: 1-0)
JPN: Homare Sawa 22'
