This technique needs two swords to perform. Once Aki imbues her swords with chakra, she begins to cut and dice faster than just the naked eye can see. Only those with the Sharingan will be able to match Aki's speed and that's if the user of the Sharingan is actually ABLE to match her speed. She invented this jutsu when training by herself and first used it in combat when she fought a hydra summoned by Heiwa Chinoike. Fuyuki copied the technique using her Yochigan but didn't master it until Aki taught it to her herself.