Once ranked as high as fourth in the world, Fowler has endured a torrid time on the golf course in recent years, resulting in him dropping outside the top 150.
His poor form ultimately ended with him missing out on qualification for last year's Masters, the first major he had missed since the 2010 US Open, and he has not been back to Augusta since.
Fowler was also coming off a missed cut at last week's Shriners Children's Open, but he followed up a solid opening 67 at Narashino Country Club with a superb seven-under-par 63 on Friday to grab a share of the lead with countryman Andrew Putnam.
The 33-year-old carded seven birdies in a bogey-free round to move to 10 under alongside Putnam, who set the initial clubhouse target after a splendid 62.
Former PGA champion Keegan Bradley lies a shot off the pace after a 65.
"I wasn't aware yet that I was bogey free," Fowler said after his round. "Felt like I did a good job of kind of just focusing, staying kind of present and trying to keep moving forward."
"I definitely enjoy myself over here and the people are awesome. It is really cool to play in front of the Japanese fans," he added.
"I'm hoping we can give them more good golf over the weekend.
"I'm very happy with where we're at. Obviously didn't have the week we wanted last week, drove it poorly, but with some of the changes we've made and to have the finish that we did at Napa [T6 at the Fortinet Championship] and kind of seeing a lot of good things, I'm definitely happy about it and excited to be here and off to a good start."
The round of the day belonged to John Huh, who started with five birdies in his first six holes and added several more to sign for a nine-under 61, lifting him into solo fourth place just two shots back.
Defending champion Hideki Matsuyama failed to make any significant gains on Friday, rounds of 71 and 69 leaving him on level par, 10 shots off the pace.
Collin Morikawa lies five shots back after a well-played 64, joined by fellow young gun Viktor Hovland.