An Astral Pouch (「異袋」?; ibukuro; stomach) is a small bag that stores Food acquired by Amaterasu during her travels. The pouch has many uses, but primarily serves as a stomach of sorts of the sun goddess.
In the River of the Heavens, Issun and Amaterasu come across a Treasure chest containing the mysterious Astral Pouch. With the later introduction of the Praise system, Amaterasu is able to acquire three more Pouches, but cannot purchase or sell them anywhere else. She can, however, purchase items to make use of these Pouches easier.
With each morsel of food Amaterasu consumes, she gains a certain number of Food points. A total is shown on the screen whenever something is consumed, and when the Pouch becomes full, turning red and reaching 200 points, food will stop being collected in that Pouch and begin filling the next, if one exists. Otherwise, the consumed foodstuffs convert to Yen that Amaterasu can use for other purposes.
Once full, the Astral Pouch acts as a revival mechanism, allowing Amaterasu to return to life should she be killed in battle. However, doing so empties one of her Pouches, requiring her to refill it either on her own once more or with a Golden Peach. Use of the Golden Peach will instantly refill an Astral Pouch, and are common rewards from many sidequests and boss battles.