New Year. Shogatsu refers to the season in general rather than just new year's day, which is ganjitsu. Shogatsu is not itself a matsuri but comprises a complex of elements such as hatsu-mode, kadomatsu, hi-no-matsuri, hadaka (naked) festivals and arguably omisoka the last day of the old year. The new year season extends to the old or Chinese lunar new year in February, marked by spring festivals (haru-matsuri) and setsubun.
A Popular Dictionary of Shinto. Brian Bocking.