The youngster says he's not wasting his time thinking about his compatriot's Celtic exit.
The Norwegian coach is set to leave Parkhead after two years in charge, having failed to secure a contract extension for next season.
The 40-year-old won one Scottish Premiership title and is on the brink of delivering another one, but a Scottish Cup semi-final defeat by Rangers, coupled with a repeated failure to reach the Champions League group stages, effectively put paid to his hopes of staying with the Glasgow giants beyond this term.
Deila has been forthcoming in his claims that he leaves a good legacy at the club, and Ajer, a winter signing from Norwegian outfit IK Start who will join up with Celtic in June, is one of the players that he will be leaving behind.
But although the 18-year-old says that he is a "fantastic" manager, the starlet acknowledges that the change of personnel does not have a major impact on him.
Ajer told Norwegian publication Nettavisen Sport, via The Scotsman: “Ronny leaving is no great disadvantage to me. He’s a fantastic coach and he’ll be missed, but I can’t waste any energy on it.
“I’ll arrive to a new coach who will look at everyone the same, and good performances will decide whether or not I play.”
Ajer, who was appointed as Start captain at just 16 years of age, certainly seems like a player with complete confidence in his ability, seemingly knowing that he will impress Celtic's next boss just as much as he did Deila.