With Honda having pulled out of F1 last year, Red Bull is stepping up with its own powertrain division to take over running of the Japanese engines.
And while during a transition phase Honda will continue to manufacture power units from its Japanese facilities, many of the staff that helped Max Verstappen secure last year's drivers' championship have been moved on to other projects.
However, it has emerged that Yamamoto, who was effectively Honda's F1 chief, is leaving the Japanese company this month to set up a consultancy that will work with Red Bull to help support its efforts.
Speaking about his plans, he said that the idea was for him to act as a point of contact between both Red Bull and Honda to ensure the relationships remain strong between both parties.
"We have established a new company," he told Motorsport.com's Japanese edition in an exclusive interview. "We want to do something that makes people happy, and if we win in F1, then fans will be happy with that.
"We've signed a contract with the company at Red Bull Powertrains. The company has me, at the request of Red Bull's Christian Horner and Helmut Marko, to support them.
"It's a contract between companies, so it's difficult to speak about details, but as one of the members of Red Bull Powertrains, I will undertake work that will help them."
Yamamoto explained that his main focus will be on acting as a bridge between Red Bull powertrains and Honda, to ensure that engine progress from now on is as smooth as possible.
"If, for example, they want to understand Japanese culture and Honda's culture, and have a closer and better relationship with Honda, we can support it. Basically it's a bridge between Red Bull and Japan."
Yamamoto expects to attend a number of races in his new role, and says the decision to leave Honda came after it made its call to withdraw from F1.
"I decided that in March of last year," he explained. "I was appointed director of motorsports in 2016, and my goal was to win the SUPER GT championship at first. I was able to achieve that in 2018 [with Naoki Yamamoto and Jenson Button].
"For the next three years, I was dedicated to F1. From the beginning, I thought that this work was the culmination of my life at Honda and I thought I could make use of everything I had experienced there.
"I was wondering if we could win with Red Bull for the first time in the first year, and then have a good [championship] fight with Mercedes in the second year. But that wasn't the case.
"But, in the third year, with Verstappen's driving ability and the strong Red Bull team we managed to win the championship."
