Robertson explained the match selection was based on a balance between opportunities for the less experienced members of the side to have a chance against Japan, while having more experienced players preparing in London meant the challenging travel arrangements of next week would have less impact on their Test against England.
"They can get into a proper Test week whereas if you play this week and then end up on a Sunday you miss two training days, so it is a chance to get a step ahead with that Test [England]."
Robertson said the side to play Japan had a good mix of experienced players in key positions and some great young talent.
Wellington flanker Peter Lakai and his Hurricanes teammate Ruben Love will have potential All Blacks debuts from the bench.
"Peter slipped straight in. We had him in for a week earlier in the year. And Ruben has been chatting with us for the majority of the year."
The choice of lock Patrick Tuipulotu as captain was down to his mana within the side.
"He's a man of few words. When I asked him, he didn't say too many words but you could tell how pleased and honoured he was."
Wallace Sititi will play at No8 in combination with flankers Sam Cane and Samipeni Finau.
Halfback Cam Roigard and fullback Stephen Perofeta are starting after coming back from injuries.
Robertson said the All Blacks coaching staff have been impressed with the young players coming through on the Japan side, and fullback Lee was an exceptional talent.
With Damian McKenzie, TJ Perenara and Cane having played in Japan recently, the All Blacks had plenty of understanding about their opposition.
"They have talked about how brave the Japanese players are and that if you give them opportunities, they can take you and punish you."
He was also aware of the input of Japan coach Eddie Jones.
"He's got great innovation, he pushes his teams to the limits and he gets the best out of people. He's done that in some key moments in his career."
The All Blacks will concentrate on finishing the opportunities they create, which has been a theme for their year.
"We want to be a little more clinical and show our skill set. We want to show Japanese rugby the All Black way because I know the Japanese will be playing a fast style, so it'll be entertaining."