Most people think of the Japanese lunar calendar as being basically the same as that used in China.
For the most part, this is true. Ancient calendar scholars in a number of cultures found that after three solar years, the lunar calendar would be behind the sun's actual progress by about 33 days. For cultures based on agriculture, this was an intolerable system. To keep the solar calendar aligned with actual seasons, it was required that the winter solstice always occur in a non-intercalary 11th month. Thus, generally in early lunar calendars, the new year began on the second new moon following winter solstice.