Ako, who appears in Onimusha 3: Demon Siege, is a young and spirited Tengu that aids both Samanosuke Akechi and Jacques Blanc in their fight against the Genma. She is a member of the Crow Tengu clan. She is introduced when Jacques arrives in Japan and meets an Oni God.
She is able to teleport between time, switching between both Samanosuke and Jacques during gameplay. She can also carry items the two give her, for the other one to use. Also, when they are found in the game, Ako can also wear different types of dresses that have different effects, which can help the two warriors as they fight against the Genma. Though she looks fairly young and can appear childish at times, Ako can be very mature, as she understands human emotions and feelings. Onimusha 3: Demon Siege has two endings, the first, Ako is seen flying alongside Samanosuke as he walks away with Gaunlet sealed, in the second, Ako takes human form and accompanying Samanosuke as he walks away.
In Onimusha: Dawn of Dreams, a human child sized priestess with similar look and abilities to Ako appears by the name of Arin, as the companion of a white-haired monk in familiar red armor named Tenkai at the ruins of the temple at Mt. Hiei. She helps Soki become the Onimusha and stays watching over Mt. Hiei while Tenkai leaves to fight with Soki's group. At the end of the game, it is revealed that Arin and Tenkai respectively are indeed Ako and Samanosuke.
- Upon closer inspection, one can see that Ako has cat-like eyes.