The Shinobigatana "Oborozuki" (in Japanese: 忍刀「朧月」, the Shinobi Saber "Hazy Moon") is Joe Musashi's iconic sword, and one of the Oboro clan's greatest treasures. His father, Jiro Musashi, wields the blade in an alternate timeline. In Shinobi and The Revenge of Shinobi, Joe Musashi used this katana to dismantle the crime syndicate, Zeed.
Oborozuki is the legendary jouningata ninjatō (in Japanese: 上忍型・忍者刀 master ninja styled ninja sword) that was crafted by the Oboro in ancient times. In contrast to the typical nihontō (in Japanese: 日本刀 Japanese sword), Oborozuki has a slightly shorter and skillfully trimmed bladed edge, with a blade slightly longer than a normal ninjatō. An excellently crafted sword, it is a weapon of battle and a historical artifact that acts as symbol of authority in the Oboro clan; the sword was given to only the most skilled and distinguished ninja of the Oboro school, and was bequeathed to many a chief of the Oboro. In the Oboro clan, it is the master ninja's badge of office.
Oborozuki was carefully crafted with secret forging techniques, and imbued with Oboro secret arts. This magnificent sword is the clan's most treasured blade. The blade has been passed down throughout the generations, and from one master ninja to the next. The legendary ninja, Joe Musashi, wields Oborozuki with grace and strength, like his predecessors before him. When the blade is used by a master swordsman, it shines with a brilliant radiance akin to a misty full moon on a spring night. It has spilled the blood of the enemies of the Japanese emperor, and also many Zeed henchmen, in the Kamakura era and in modern times.
- Joe Musashi: Oborozuki was bequeathed to him by the Oboro clan chief. Joe used this legendary blade to bring down Zeed and it's many affiliates.
- Oborozuki has a counterpart called "Oboro-Kage" which was forged by the same blacksmith long ago. It is possible that this is the katana used by Joe's father Jiro Musashi in Shinobi 3DS.
- In The Revenge of Shinobi, when Joe acquires a Power Pack, he walks in juumonji uke no kamae (十文字受けの構え; cross posture), which enables him to block attacks and slash with Oborozuki.
- In Shinobi and Nightshade, the mystical Oborozuki can obliterate Hellspawn as easily as Akujiki, though it does not consume Yin.
- In Shinobi 3DS, Oborozuki is inscribed with ancient Japanese runes carved into the blade.
- in Japanese, Oborozuki means "hazy moon". In Japanese art and aesthetics, a hazy moon is considered a sign of spring, and it is contrasted by the bright full moon of autumn. Recently in popular culture, the hazy moon has taken a romantic and fantastical association with the ninja.
- Oborozuki is also the name of a recurring ninja sword in the Final Fantasy series. It originally appeared in Final Fantasy VI, and was only able to be equipped by the mysterious ninja Shadow.