Lunar New year and Japan:

The term "lunar New Year" refers to the New Year in the lunar calendar that Japan had adopted before 1872. After the calendar was changed to the Gregorian calendar, a type of solar calendar currently used in Japan, in 1873, the lunar New Year is called "Kyu-Shogatsu" to distinguish it from the New Year in the lunar calendar. While the Gregorian New Year's Day is fixed as "January 1 every year," the Lunar New Year's Day falls on "the day when the new moon appears between mid-January and mid-February," so the date differs every year.

In regions such as China, Taiwan, Singapore, Korea, Vietnam, and Malaysia, the Lunar New Year is still celebrated with great fanfare, but in Japan, the Lunar New Year is not celebrated, which is rare among Asian countries.

Japan, too, was originally based on the lunar calendar, so of course it celebrated the Lunar New Year. However, after the Meiji government abolished the lunar calendar and the Emperor issued an imperial edict to change to the new calendar, the idea that the new calendar was more correct spread throughout the nation.

Resource: https://www.jluggage.com/blog/japan/does-japan-celebrate-lunar-new-year/