The tattoo is a clear tribute to Donna Rose Torres, the person he feels is easily the most influential in his life.
"It's a strong relationship, ever since I was a little boy," said Napoli. "My mom worked two jobs to make sure I had everything -- me and my brother. She always made sure I was at practice on time. She made sure I had the right equipment. There's a real strong bond between me and my mother."
And even though Napoli is 32 years old -- and the owner of a World Series ring -- he still appreciates the presence of his mom every bit as much as when she was getting him to those Little League practices.
When the Red Sox play the Rangers in Texas for this Mother's Day weekend, Torres will be in the stands cheering on her son. Baseball players always have games on Mother's Day, and Torres flies to wherever Napoli is that particular year.
As the Red Sox made their way through Tampa Bay, Detroit and St. Louis in last year's glorious postseason, Donna and her husband, Rick (Napoli's stepfather), were everywhere.
"We're still really close," said Napoli. "She's just a wonderful lady. She's good to everybody, no matter who you are. She's amazing. I looked up to her when I was younger and saw how hard she worked to make sure everything was good for us. It's just a strong bond between me and her that will never go away."
Donna loved the tattoo tribute, but can't help but teasing her heavily inked son.
"Now I tease him because there's so much other stuff around there, and I say, 'Now it's camouflage,'" Torres said. "I was like, 'Come on.'"
Of course, you could get just as much of an illustration of the kind of warmth Torres creates for her family by pictures of the family's Christmas-time gatherings, when someone's face is inevitably covered in flour due to the revelry that takes place during the cookie cook-offs.
"Every year, when he comes home for the holidays, there's five kids, and we do a Christmas cookie bake at the house, and it's more of a competition kind of thing," Torres said. "You should see him with the blender up to his elbows. He doesn't let anyone get near him. By the time the cookies aren't even finished, there's a flour fight in my house.
"It's just, that's what kind of family we are. We're lots of fun. All five of them are close. We're a very close-knit family. We do a lot of traditional things and fun things. Mike's real good. He's been taking care of everybody. It's just been a dream come true."
The fact that Napoli is still a bachelor has allowed his mother to continue to nurture him the same way she did many years ago.
When the first baseman recently bought his own place in Boston, his mother completely arranged it for him.
"She loves coming here to Boston," Napoli said. "She set up my whole place. I let her design my whole place here. She loves that kind of stuff. She does anything for her children. It's not just me, but my brother and sister. Any time we need something, she'll bend backward and do anything. Even if she has something crazy going on, she'll drop everything and do anything for us. She's just a great woman."
Fittingly, the only time Napoli gets upset at his mom is when she wants to head back to her home in Florida after visiting her son in Boston.
"Every time we go, it's so funny, because he'll say, 'Don't you want to stay an extra couple of days?' It's always a couple of extra days," Torres said. "I love it. We stay at his place. I get up and he'll leave and I'll make his bed and my husband cooks him breakfast. So yeah, we have a really, really tight bond. We're very close."
A life-long resident of Florida, Mike Napoli can't wait to have his mom and the rest of the family spend Christmas with him in Boston later this year.
"We've never had a white Christmas," noted Napoli.
Torres laughs with her son about how life might change once he settles down and gets married.
"I always joke with him that I'm not really in any hurry for him to get married. It's just a joke. Of course I want a daughter-in-law and grandchildren some day when he's ready," Torres said. "He's not ready right now. I always joke with him, I say, 'I'll stay on that No. 1 spot as long as I can be there.'"
Napoli recently bought his first fancy car, and he couldn't wait to share the news with his mom.
"He just texted me a picture of his new car. And this is the first really nice car he's had," Torres. "Michael isn't the type of player that just went out and bought this house and that house and all these cars. He's had the same vehicle since he got called up to the Majors. He finally treated himself to a really nice car, and he sent me a picture of the car. I said, 'You know what, Mike, it's hard work and dedication, you deserve this, and I'm so happy for you.'"
When Mike Napoli grew the beard of all beards last season -- one that grew longer and became more beloved by fans with each October win by the Red Sox -- his mother had the reaction you might expect.
"At first, I used to get on his case about it," Torres said. "And I was like, 'Why are you covering up that face that I made?' Everybody got on him about it. He said, 'The more people bug me, the more it's going to grow.' Then it became a part of him.
"Do I honestly like it? No, I'd rather see him shave it. But it has become a part of him now, so I got used to it. My dad -- Mike's grandfather -- he's always like, 'Tell him to shave that face.' I'm like, 'Dad, it's not going to happen. Just forget it.'"
But Napoli never forgets his mother's impact on his life.
"People say, 'You were raised right,'" Napoli said. "I go straight to, 'That's because of my mom.' My mom was one who showed me the way, showed me how to be the person I am today. She's special to me."