O sacred moon of the heavens, come forth and pierce this darkness! Bear witness to the beast's demise upon my trusty sword Tohenboku!Susano
Tohenboku (「唐変木」?) is Susano's sword in Ōkami and Ōkamiden. At several points in the first major arc of Ōkami, Amaterasu must use her Power Slash in sync with Susano's attacks with Tohenboku to slash targets and enemies that Susano cannot even destroy on his own. After the Orochi battle, the sword turns to gold and is rennamed Susano Blossom.
The first time Amaterasu witnessed Susano using the sword was in Kamiki Village. In order to get Susano to destroy the rock that he blocked the village's exit with, Amaterasu had to help Susano destroy his practice dummies to give him the confidence to destroy the rock. Amaterasu did this by using her Power Slash at the same time he struck a dummy to make it appear as though his wooden sword had cut them. Susano then proceeded to use his technique, Susano-Style Exploding Implosion, on the boulder and Amaterasu used her Power Slash again and the boulder shattered, much to everyone's surprise.
When Amaterasu returned to Agata Forest in her search for the Eight Canine Warriors, she helped Susano defend Kushi from several Imps. Susano attacked the Imps, but it was Amaterasu who killed them by using Power Slash immediately after Susano's attack.
During the battle against Crimson Helm, Amaterasu once again helped Susano use the sword, this time to destroy Crimson Helm's Orochi apparition, before summoning a wind with Galestorm so Susano could cut Crimson Helm himself.
The final time Amaterasu assisted Susano was during the battle with Orochi. Susano asked the gods to lend him the power to defeat the serpent. With a howl, Amaterasu used Crescent. The sword resonated with the moonlight, turned gold and grew a flower where there had once been a leaf. Susano gave his empowered blade the name Susano Blossom. Amaterasu then helped Susano destroy seven of Orochi's heads before Susano killed the final one on his own.
After the battle, Susano remained in Kamiki Village to train with the sword.
Susano still carried Tohenboku when he met Chibiterasu. The blade retained its flower but returned to its plain, brown state.