Enjoying the benefit of a 10-2 penalty advantage, All Blacks captain Kieran said: "Discipline was always going to be a massive thing for us. South Africans love to build pressure through those penalties and with a kicker like [Handre] Pollard he showed right from the outset he could kick from 50m.
"It was a conscious decision from us to make sure we didn't give away too many penalties and we probably haven't been as smart throughout this whole year and we were certainly at a different level today," he said.
Coach Steve Hansen was pleased with the win, although he admitted the outcome still left plenty for the All Blacks to work on.
"Everyone knew this was going to be a big match and obviously it was. I thought both teams played very well at times and very happy to come out with the win."
He explained an apparent mistake that did not allow flanker Sam Cane to return to the field after he had an HIA.
Hansen said that a sideline match official thought Cane had overdone his time for an HIA.
"He passed the test, he was as good as gold," he said.
They had since talked to the match commissioner and they would have a discussion to rectify the situation for future games.
Read said South Africa's defence had been strong across the game and they had kept coming at the All Blacks which was what they expected.
"What you can't do early in a game sometimes is get those balls away so you've either got to get deeper or try to work on your skills. Really it took two opportunities from us in that first half and I guess we managed to take them and we will have to work on doing it a bit more regularly in future games," he said.
Hansen described first five-eighths Richie Mo'unga's cover tackle on Springbok wing Cheslin Kolbe as a matchwinner. A try appeared a certainty as the flier got room but Mo'unga pressured him towards the sideline and then executed a superb tackle.
"I thought our scramble defence tonight was really, really good. They hurt us a couple of times, as we did, from high kicks and making breaks but the boys got back really well. Rich got back and saved that one. It was a pretty big moment but that's what rugby's about, trying to win the moments that matter," Hansen said.
"The boys showed a lot of fortitude, we didn't get too many opportunities and we took them," he said.
It had been hard early in the game for the All Blacks to play as wanted because their set piece hadn't been as good as they wanted it to be and they didn't have a platform to strike off.
They had adjusted and there was more fluidity as the game went on.
"You can't strike if you don't get TQB, top quality ball, at the set piece," he said.
Read said the gesture of bowing to the crowd at the end of the game was an acknowledgment to Japanese fans that the All Blacks valued their support.
Assistant coach Ian Foster said he felt fullback Beauden Barrett was keen to have an impact with the side at the tournament.
"He's been building for a while, he's a key part of our whole strategy group. I know how focused he is on playing well – there's a few others like that too. He's working well and growing the confidence of other guys to make decisions, I think helping Richie grow in the position that he's in and also our midfield are making a lot of decisions.
"He's a part of encouraging them and giving them confidence too," he said.