Overview
In Japan, children begin mandatory Elementary education, when they're just 6, and so cyuuut!! And move on, to Junior High School, once they reach 12!!
Uniform
While most Elementary Schools in Japan, don't mandate students, to wear designated school uniforms.
In popular media, they're still often portrayed wearing them.
They may also be required to wear (上履き) uwabaki, a type of soft indoors slippers, within school premises.
Girl Uniforms
Girls generally wear uniforms, stylized after the (セーラー服) sērā fuku, "Sailor Outfit", uniforms introduced back in 1920.
The uniforms, often features a blouse, with sailor styled collar, and a pleaded skirt. While colors may vary, generally they tend to be navy-blue.
They also wear white socks, and red/white shoes.
Boy Uniforms
Meanwhile boys, wear more a more formal attire, stylized after the (学ラン) gakuran, Rough translation: "Western Style Student Outfit." Uniforms, introduced along the same time, the sērā fuku were introduced.
They feature, a navy-blue/black jacket, decorated by metal buttons, going top-to-bottom, and straight pants, though more often, short trousers, along with white socks, in leather shoes.
They also sometimes, wear a bowl shaped cap.
Backpack
Elementary Schoolers, are well known for their signature backpack, a red (ランドセル) ransel, or randoseru.
It's a Netherlands-style rucksack, made out of either stitch leather, or synthetic kinds.
Well known for it's design, being a rectangular shaped, divided compartment backpack, with a round top, and hard sides.
The rear features an unique flap, running across the entire length, of the backpack.
Which also functions as the primary, opening/closing mechanism.
Miscellanous
In popular media they're generally equipped with a yellow security buzzer, primarily attached to the shoulder straps, or their uniform.
With the aim, of warding off spooky predators, looking to prey on unattended school children.
Disclaimer
I made this, primarily as a joke ーωー
Original thumbnail: https://www.pixiv.net/en/artworks/13010031