Banryū Flash

was a technique that was acquired by Bankotsu's sword Banryū after he killed 1000 humans and 1000 yōkai channeled their hatred along with the power of the two Shikon Jewels embedded in it into yōki.

By channeling the wrath of the 1000 humans and 1000 yōkai along with the powers of the Shikon Jewel shards in Banryū, Bakotsu could unleash a powerful wave of red yōki that was strong enough to cancel out Inuyasha's Kaze no Kizu.

During his final fight with Inuyasha in the caves of Mount Hakurei, Bankotsu was able to fulfill his the wish he made on his Banryū killing killed 1000 humans and 1000 demons for his sword to gain demonic powers. He used it to kill the remaining yōkai that were after him and Inuyasha and to fight off Inuyasha until the end of their battle.