Collin Morikawa admits 'winning is tough' ahead of Japan title defence
The American romped to last year's title at Narashino Country Club near Tokyo by six shots to end a two-year title drought.
He has not lifted a trophy since and described his 2024 season, which has included two runner-up finishes, as "solid" rather than spectacular.
Morikawa was part of the United States team that beat the Internationals at the Presidents Cup in Montreal last month and is hoping to keep that form going this week in Japan.
"It's a place I look forward to every year. Knowing that I won last year, lot of good memories," said Morikawa, who has Japanese heritage.
"It was my first win in two years. Look, winning's tough. No matter what it is, winning is tough. You have to learn how to win."
Morikawa will be up against fellow American Xander Schauffele, who won the PGA Championship and British Open in a breakthrough 2024, and Japan's Olympic bronze-medallist Hideki Matsuyama.
Morikawa finished runner-up behind Scottie Scheffler at the season-ending Tour Championship last month but said "you just never know what to expect" when play begins.
"Every tournament's different, you never know how you're going to play on a Thursday, Friday, Saturday, Sunday," he said.
"You've got to treat each day and each shot and take everything that's in front of you, and not take anything for granted."
Morikawa struggled to keep his emotions in check when he lifted the Zozo Championship trophy last year.
"Honestly, I'm not that emotional of a guy," he said.
"Whenever something happens, you just never know what it's going to be."