In Bleach, there is a squad of shinigami samurai, their leader is [a very old man](https://static0.gamerantimages.com/wordpress/wp-content/uploads/2022/04/Bleach-Genryusai-Yamamoto.jpg) named ‘Genryusai Shigekuni Yamamoto’. ‘Genryusai’ is a nickname, an adopted title Yamamoto took on.
Originally, Yamamoto was called “Eijisai” because the[ scar on his forehead looked the character Ei](https://static.wikia.nocookie.net/bleach/images/0/05/504Younger_Yamamoto.png/revision/latest?cb=20170829011056&path-prefix=en), later he got another [scar and was called “Jujisai”](https://static.wikia.nocookie.net/bleach/images/3/37/504Yamamoto_is_scarred.png/revision/latest/scale-to-width-down/190?cb=20170829011112&path-prefix=en), but a dear friend continued to call him “Eijisa”, so in order to honor him he went by then name “Genyrusai”. He was inspired to do so by looking at a Willow tree.
Can anyone explain the relationship each of the names and characters have to each other? How does ‘Eijisa’ and ‘Jujisai’ combine to form Genryusai, where does the willow tree fit in, and what exactly do all of these names mean?