@xiaopangshizi i found the story of your tsuba.
It's from nihon shoki poem
"Agatamori battling mizuchi in the pool"
Here a passage of wikipedia
"The ancient chronicle Nihongi contains references to mizuchi. Under the 67th year of the reign of Emperor Nintoku (conventionally dated 379 AD), it is mentioned that in central Kibi Province, at a fork on Kawashima River (川嶋河, old name of Takahashi River in Okayama Prefecture), a great water serpent or dragon (大虬) dwelt and would breathe or spew out its venom, poisoning and killing many passersby.
This mizuchi was exterminated by a man named Agatamori (県守), ancestor of the Kasa-no-omi (笠臣) clan. He approached the pool of the river, cast three calabashes which floated to the surface of the water and challenged the beast to make these gourds sink, threatening to slay it should it fail. The beast transformed into a deer and tried unsuccessfully to sink them, whereby the man slew the monster. The record goes on to say: "...He further sought out the water-dragon's fellows. Now the tribe of all the water-dragons filled a cave in the bottom of the pool. He slew them every one and the water of the river became changed to blood. Therefore that water was called the pool of Agatamori"."
Could you make 2 good pictures of the tsuba front and back for my archive? I like that motif and story very much.