The answer is “Uwabaki (indoor shoes) “

This is footwear for school. It looks like slippers.

Why there are “Uwabaki” in Japanese?

Maybe, you know we Japanese always wear and take off own shoes when we enter to house and school. That’s because it has a hand in Japanese culture. Japanese buildings had rooms which floor was all tatami a time in the past. Early people took off their shoes at the front door and they came in their houses with bare foot. Incidentally, they always sat on tatamis directly. There were no chairs in those days. That is to say comparison Japan and foreign country, Japanese take it for granted that they sit on the floor directly. So, we didn’t make it a rule to wear slippers in house. We still have a tatami room and some rooms which has wooden floor in our house. Someone wear their slippers in own house. But anyone always take off own slippers when we go in the tatami room. That’s why there is some hesitation not to take off our slippers. This feeling is just peculiar to Japan and equal the feeling which arise from to enter the house and school buildings with own shoes on. So, we always wear “Uwabaki” at school and wear slippers in the houses.

By the way, in Japan, students at preschool, elementary school and junior high school wear it. If it’s worn by junior high school student or about over 10, slippers are better than “Uwabaki” because slipper doesn’t constrict our feet so, we can relax. But, preschool student is very activity. So, wearing slipper is dangerous for them because it’s very easy to get out theirs slipper. Therefore we have children of activity to wear shoes are heeled are made by elastic. If they were tumble for shuck off them slipper, they would had injury. And it’s very cheap and it has good keeping because it’s often made by vinyl. So it’s set down by many preschool and another school.