"It's so exciting. I'm very glad to be back," said the 29-year-old through an interpreter. "I don't think the team has been struggling. I know that Aiden McGeady has had some great performances recently. If I can do the same on my side maybe it will make it easier for Aiden."
Asked to respond to rumours that Yokohama Marinas would like to take him back to Japan, Nakamura joked that he will be ready to return to his homeland "when Peter (Lawell, the Celtic chief executive] says 'I don't need you any more'."
Nakamura has proved valuable on and off the pitch for Celtic, but won't outstay his welcome.
"Of course I will go back to Japan eventually, at time in the future," he added. "I don't want to finish my career away from my home. Marinos was the club I started my professional career with, so that would be great if I could go back there."