entrance ceremony
A school entrance ceremony, called Nyuugakushiki (入学式) in Japanese, is the welcome ceremony for incoming students to a school.
While entrance ceremonies are held at various times around the world, in Japan, where most of Danbooru is based, they occur in April when the cherry blossoms are in full bloom.
Common scenes include students in school uniforms with their parents at the school's gates, with cherry blossoms and a sign or banner that says "入学式".
There might be a younger version of the character.
The tag is not limited to images of school gates and banners, but use your best judgment in deciding whether an entrance ceremony is depicted.
See also
Commonly seen
1) New students entering the ceremony hall (usually a school gym)
2) The principal makes a speech
3) A representative for the new students take a pledge concerning their new school life
4) Students sing their school's song