The death of your heart will cause you to forget all of the most important things. People think memories are kept in your brain, but that's not true. Your heart is where all of your most precious memories are kept, and when it dies, you forget them all.
When someone forgets everything they're left with only one thing to do: go bowling (ぼう). Bowling is easy, and there's nothing to forget. You pick up a ball. You drop it. Everything else is automatically taken care of.
Currently there are no similar looking kanji which exist in the WaniKani learning system