Belgian striker Mertens has played a key role in Maurizio Sarri's men establishing a one-point lead over six-time defending champions Juventus in the race for the Scudetto and, having rebuffed interest from China last year, the Belgium forward is loving life in Campagnia.
He told Il Mattino: "I'm playing and having fun on the pitch and I’m very happy. I'm happier now than I've ever been before.
"I feel like a kid in a toy store at Napoli and I feel like I can see all of my wishes come true."
On a potentially lucrative deal in China, he added: "It happened last year, this year nobody called me.
"The temptation was there, it's normal and human, but I wanted to stay here. And I still want to stay here."
Napoli visit rock-bottom Benevento on Sunday with Mertens willing to play anywhere to help Napoli break Juve's domestic stranglehold.
"To win the Scudetto I'd play full-back and goalkeeper if Sarri asked me to, even if [Pepe] Reina wouldn't be too happy!"