If your fingers are strong enough you can take an axe and fold it in half. Bad men were cutting down all the forests, so you're going around bending their axes so they can't cut trees down anymore.
Unfortunately, as you fold these axes in half you realize they come in sets (せつ), so there are twice the axes you thought there would be. To compensate, you start folding them in sets too.
Currently there are no similar looking kanji which exist in the WaniKani learning system