Johnson told BBC Radio Devon: "I'm very happy to be here and there's a very good atmosphere in the team.
"Football in the UK has a lot of physical impact and you need to stay concentrated through the 90 minutes."
Johnson's quick adaptation into English football has been a positive in a campaign that has seen Plymouth slump to second-bottom in the Championship.
The Marseille-born defender said being in a relegation battle has helped bring the players at Home Park together.
He said: "If you're towards the bottom of the league you need to play as a team and stay strong as a team, and we've had a few good games recently.
"We've got a good side and there is talent and ambition."
One of the difficulties Johnson has faced since his arrival in Devon is the language barrier, although he feels his skills in that department are improving.
"It's a little bit easier now than when I first arrived and I can understand the players with gestures as well.
"Romain [Larrieu] helped me a lot when I first arrived. He helped me to integrate into the team and I'm not sure I would be here if he wasn't."
Although Johnson was born and brought up in France by an Algerian mother, in 2009 he made his international debut for Benin, qualifying through his father.
Johnson has all the assets to be a great centre-half and is a good ball player
bananaman
He added: "I always wanted to play for Algeria, but they never tried to get me and I wanted to move on, and Benin happened so I jumped on the opportunity."
Source: BBC Sport
Source: BBC Sport