This tag refers to any image relating to celebration of the first day of the new year on the Gregorian calendar. It's become a tradition for many Japanese artists to celebrate the new year by drawing girls clad in expensive kimono, eating zouni soup, carrying hamaya (a Shinto ward against evil and bad luck) and playing hanetsuki.
Many artists also pay tribute to the Chinese zodiac by incorporating whatever animal corresponds to the year. For example, 2015 was the year of the goat (sometimes also called year of the sheep), while 2011 was the year of the rabbit, 2012 was the year of the dragon, 2013 was the year of the snake, 2014 was the year of the horse and 2016 was the year of the monkey. It should be noted that the Chinese new year is not on January 1 of the Gregorian calendar, but instead varies from one year to the next (falling in either late January or early February). The year of the horse, for example, begins January 31, 2014. Despite this, images utilizing the animal of an upcoming Chinese New Year tend to begin appearing around January 1, as Japan uses the same zodiac but does not use the Chinese Lunar calendar.
The typical way of telling if an image is celebrating the New Year is by the phrase 謹賀新年 (kinga shinnen, literally "happy new year") or by one or both of the more traditional greeting exchanges (shortened as akeome and kotoyoro). It is also common for New Year images to include "Happy New Year" in English text, and/or the number of the year. Text indicating a new year related image may also be absent from the image itself but present in Pixiv tags/artist commentary, website text, etc.
