With a thread, a lion sews together all the rice he'll inherit from his parents one day. He's convinced his parents are going to try to keep some of his inheritance from him, so he's linking it all together so it can't go anywhere.
If you're going to inherit something from your parents, try to convince them to make it cake (けい), not rice. A single cake is much easier to keep track of and probably tastier (though it will be super stale by the time they die).
Currently there are no similar looking kanji which exist in the WaniKani learning system