The Norwegian arrived from Stromsgodsets, surprise title winners in his homeland, in January and quickly became a regular fixture in Neil Lennon's starting line-up.
The 23-year-old has also adapted well to life off the park in Glasgow, which is sometimes a struggle for foreign players who sign for the Old Firm.
His fellow January signing, Leigh Griffiths, is finding out about the added scrutiny on Celtic players after being investigated by police over alleged "racist chanting" after footage emerged of him in a pub with fellow Hibernian fans.
But Johansen said: "I think the people, not only in Glasgow, but all Scottish people are very nice. When you go to restaurants, they are nice to you.
"When someone comes to ask for a picture, it's always nice. I have never had a bad experience.
"That's how it is in a club like Celtic. You are a player for a huge club and the club means a lot to the city. But it's only positive.
"Also, it's important to give something back to the fans. They come week in, week out. If you are out shopping and they ask for a picture, of course you give it. Just be nice and they are nice to you."
Celtic are also investigating the allegations against Griffiths, whose signing Lennon was forced to defend from criticism in some quarters.
But the manager's Celtic future is also the subject of speculation after he emerged as one of the favourites to be installed as Chris Hughton's permanent replacement at Norwich.
And Johansen would be disappointed to see Lennon go after forging a strong relationship during their short time working together.
"Of course it would be sad because I think he's a fantastic manager," the Norway international said.
"He brought me over here and we have a good relationship. He has let me play from the moment Joe (Ledley) left the club.
"He helps me a lot in training and he is a very good manager so I will be sad if he goes.
"He knows what the club is for and he knows how to win. He creates winners and losing is never an option for him.
"He gives young guys a chance also. That's important for a manager, to give players a chance, and it's good to back up young guys and new guys.
"But he demands to win and that's what I like about him as a manager."
Johansen is relishing the prospect of European football at Celtic Park and he believes it offers real incentive for Lennon to stay.
"First of all we have to finish this season and start to prepare for the Champions League," he said. "We can qualify for the group stage for a third time in a row. So we have more to achieve here and every player wants him to be here."