Who is Aoi from The Infernal Desire Machines of Doctor Hoffman: A Novel and what is their importance?

Aoi is Nao-Kurai's nine year old daughter. After saving a fellow tribesman from being cheated by a land person, Desiderio is given the honor of marrying Aoi. The child begins coming to Desiderio at night after the engagement is announced. Desiderio is not allowed to consummate the relationship, but the girl uses some very grown up skills to give pleasure to Desiderio. Desiderio is not in love with Aoi, but he is content with the relationship and happy to be made a part of the tribe.