This year it was still called 150 class but the class was extended to 159.9 max legal weight
From Japan open site:
Sanctioned as a "150-class" PDGA Major, players can thrown only discs that weigh-in at less than 159.9 grams. This is a legacy from where the event originated in the highly populated Tokyo city park courses three decades ago. This lighter class of discs requires a steep learning curve for our players under the best conditions, but can also be a huge liability with the winds that are known to course down the Nasu Highlands mountainside during this beginning of the annual rainy season in Japan.