More mystery Hanko

Here is the Hanko from a shakuhachi that I purchased 5 years ago from "The Japanese Gallery" in London. It was sold as 80 years old, but with no evidence.



It seems to read 廿　（にじゅう）　at the top and 巴　（ともえ）　also on the left is a large "L" which could be somthing like 凹　（ぼこ）、 also included are what seem to be two birds maybe? But could posibly be 卍 but that does not seem likely. The birds could also be the forked tounges of snakes as tomoe looks like snake...

Fascinating!

If you have any ideas as to the reading or the maker, please do post!