There is a prison on a cliff surrounded by snakes. Now that's a dangerous place. If you try to escape the prison you either fall to your death off the cliff or get bitten/squeezed to death by the snakes. Can you think of anything more dangerous than this? I can't.
Lucky for you, even though you're stuck in this dangerous place, there is hope. There is a key (き). All dangerous prisons have a key. You just have to find and steal it so you can avoid the cliffs and snakes!
Currently there are no similar looking kanji which exist in the WaniKani learning system