Unko Sensei (literally Poop Teacher), is a charming mustachioed turd helping Japanese grade-schoolers learn over 1000 kanji characters required by the end of 6th grade.

Via Tokyo Weekender:

While it may seem like a bad idea to encourage toilet humor in an age group that's already obsessed with it, the appeal of these books is that they aim to make studying fun and encourage kids to study independently. With example sentences like the ones below, it's easy to see why that would work:

Take 六, the kanji character for "six" from the grade one drill book. Here are the example sentences, from left to right:

1. I won't poop until June.

2. Let's combine these six poops into one.

3. I had a poop with the same shape as one I had six days earlier.