Johnson, who only made his debut for the Stags this year after toiling away in the reserve sides for two years, had initially just hoped to secure a contract with the team.
When he was called up to the top side, the midfielder quickly became the standout Stag, being the only player to start all 10 games in what was a winless campaign.
In a team that was continuously going backwards, his direct running made him a consistent attacking threat that opponents struggled to manage.
It was initially the national sevens setup that noticed Johnson’s skills, and he was selected in the All Blacks sevens development that will be playing in the US this week.
That was until word came through that the Blues were interested in him, so he pulled out of the team, and two days later he was contacted by Blues coach Tana Umaga.
“It’s unreal. I was just trying to make the (Southland) 23 this year and it has all just fallen into place. It hasn’t really sunken in, I think everybody else around me was celebrating more than I was,” Johnson told Stuff.
The fact he is originally from Auckland and the surroundings are familiar will help ease the nerves a little as he prepares for his biggest rugby challenge yet.
“It’s where I grew up, so I’m pretty happy I get to go back home.”
Johnson, who played rugby league for the Melbourne Storm under-20 team after leaving school, said he hasn’t yet sorted anything as far as a provincial contract for next year.
At the Blues, Johnson will have the opportunity to learn from the legendary Sonny Bill Williams.
Loose forward Murphy Taramai also was selected for the squad, and will learn from the likes of Jerome Kaino and Akira Ioane.