Level, Grade, Rank
There are pieces of thread on each escalator showing you what level they go to in your school. Each escalator takes you to a different grade, so make sure you follow the right thread or you'll end up in a class that's either way above or way below your level.
When you level up your Japanese skills, you'll take this escalator to rank up too!
きゅう
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You want to see what the highest level is, so you go up the wrong escalator. At the top you find a giant cucumber (きゅう).
A teacher comes over and says, "Excuse me, this is advanced level cucumber studies. I don't think you're at this level yet... please take the escalator down and follow the threads to find your level."