Tōu

was once a member of the Twelve Guardian Ninja. Tōu appears to be the only female member of the 12 Ninja Guards of Fire.

Background
While she was still alive she was part of the Twelve Guardian Ninja. Ten years before the start of the series, six of the members tried a coup d'etat. She, alongside Asuma Sarutobi, Chiriku, Kitane, Seito, and Nauma, fought against them, only to be killed by Kazuma when Tōu and the three other survivors tried to use Limelight on him.

Abilities
She has an elemental affinity for lightning. When in the the four cardinal directions Tōu, Kitane, Seito, and Nauma could use a jutsu called Limelight to reduce everything within that area to ash.

Twelve Guardian Ninja arc
In the anime, Tōu's, Kitane's, Seito's, and Nauma's corpses are stolen by grave robbers, and later revived using lightning. After being revived they were all approached by Asuma who had figured out the scheme of the robbers. There he tries without luck to stop the three who seem to have become mindless puppets. She started walking towards an unknown point emitting large amounts of lightning, only to arrive and prepare her part of the Limelight technique. When Kitane was killed by Asuma Sarutobi, Kazuma's plan failed and he decided to release the summoned Nauma, Tōu, and Seito.