Murakumo means massed clouds i think this particular use comes from the legendary sword called Kusanagi-no-Tsurugi (Grass mowing sword) originally called Ame-no-Murakumo-Tsurugi (Sword of the Gathering Clouds of Heaven) which dark sould shortened to Murakumo, in any case this is a very cool piece of art thank you for the upload.