A tsunami is coming, and you want to walk over it, so you have to ford it. Think about it – you ford a river, you ford anything that’s water, unless you’re Jesus – you’re not Jesus. You don’t walk across a tsunami, you ford it.
Your ability to ford this tsunami impresses everyone who witnesses it, especially the Shougun (しょう). Now that you've taught him a tsunami can be forded, he's going to start sending his troops through them instead of waiting for them to pass.
Currently there are no similar looking kanji which exist in the WaniKani learning system