Katsuragawa makes it back-to-back DP World Tour wins for Japan
The 25-year-old had seven birdies and no bogeys to finish on 17-under par after equalling the course record, three strokes ahead of Sweden's Sebastian Soderberg at the Taiheiyo Club in Gotemba, overlooked by Mount Fuji in central Japan.
It was the first time that Japanese players had won back-to-back DP World Tour events, following Keita Nakajima's victory at the Indian Open earlier this month.
Katsuragawa's win was his first on the European-based circuit and his reward was a DP World Tour card.
He will enter the top 25 of the 2024 Race To Dubai standings as he pursues his dream of playing on the US PGA Tour.
"I have been practising a lot to stand on the big stage," said the world number 434.
"I can now go on the DP World Tour, which is really great and I'm really happy with it. I'm aiming to become a member of the PGA Tour in the future."
Before last year, there had only been four Japanese wins in the history of the DP World Tour, formerly the European Tour.
The total has doubled in just seven months, with Ryo Hisatsune's win at the 2023 Open de France being followed by Rikuya Hoshino's victory at February's Qatar Masters, before the exploits of Nakajima and Katsuragawa.
Katsuragawa went into the final day three shots off the lead and two birdies on the front nine kept him in the mix.
He rattled in five more after the turn and held his nerve with pars on the final two holes.
"I was very nervous on the back nine -- my hands were shaking but I trusted myself and managed to bring my golf," he said.
"This course is beside Mount Fuji and it is beautiful but it is a challenging course."
Spain's Ivan Cantero, Germany's Marcel Schneider, South Africa's Christiaan Bezuidenhout and Japan's Ryosuke Kinoshita all finished two shots behind Soderberg in a tie for third.
Overnight leader Casey Jarvis suffered a final-day meltdown with five bogeys on the front nine, eventually shooting a 74 to finish eight strokes off the pace.
Germany's Yannik Paul, who started the day one shot behind Casey, also dropped out of contention and finished 11 shots behind Katsuragawa.
Katsuragawa won the inaugural ISPS Handa Championship title in 2022, when pandemic restrictions meant the competition was sanctioned only by the Japanese tour.