The friendship has included offseason skating sessions, and Yamamoto said he has gotten great advice from Johnson.
"Just be a leader on the ice and off the ice," he said. "I always look up to him because he's so mentally focused on our workouts and whatnot. Just getting to the next level, talk about how to get to the next level and whatnot. So it's good."
Yamamoto, a native of Spokane, is used to succeeding regardless of the age or size of the competition. He often played on youth teams with his brother, Keanu, 21, a forward who plays with him in Spokane.
"I just learned to adapt and play with bigger guys," Yamamoto said. "That really helped me growing up, playing with bigger guys. And going into the [WHL] and being a smaller guy my whole career, that really helped me out a lot."
Nachbaur said he and his staff knew about Yamamoto during his minor hockey days in Spokane, but really took interest when he began playing with the Los Angeles Jr. Kings. Spokane selected Yamamoto in the fifth round of the 2013 WHL Draft, and in Yamamoto's first training camp, Nachbaur recognized they had found a special player.
"We thought he could thrive, just because in his age group he had skill," Nachbaur said. "We saw that, we saw his niftiness with the puck, and his hockey sense was outstanding. But he was very competitive, and to play in the Western Hockey League you have to be a competitive guy whether you're a big guy or more so when you're a small guy. He had that when he was in bantam. And his first camp with us he really excelled. The things that come to mind with him is he's very creative but he never goes second to pucks, which is a compete thing. That's a really important step to playing pro. You're going to play against bigger guys, you have to be competitive. But we saw that at an early age with him. He always excelled in his age group. He was always one of the top players even when he was one of the younger guys on the team."
Yamamoto helped the United States win the bronze medal at the 2016 IIHF World Under-18 Championship. He was the third-youngest player on the team but tied for the tournament lead with seven goals.
His linemate was Clayton Keller, who was taken by the Arizona Coyotes with the seventh pick of the 2016 NHL Draft. Keller, also a smaller-stature player at 5-10, 168 pounds, said he was impressed by how Yamamoto approached the difficult areas of the ice.
"He's a special player," Keller said. "Not the biggest guy, like me, but he's good in the corners. He's small and shifty, he can pass the puck and shoot it. … Definitely plays bigger than he is. He plays like he's 6-2 but he's 5-7. He's a special player."