Kagotsurube

Cannot be auctioned, traded, or bazaared, but can be delivered to a character on the same account.
Can be obtained as a random reward from the Gobbie Mystery Box Special Dial and similar sources.

籠釣瓶 is the name given to the blade from the Kabuki tragedy 籠釣瓶花街酔醒 Kago-tsurube Sato-no-Eizame helping establish the legendarily cursed status of swords crafted by Muramasa. (Wikipedia). The name itself means "well bucket made from a basket," i.e. a bucket that holds no water, allowing it to flow freely in every direction, a poetic visualization of the nature of cuts made by the sword. (JP Wiki)