This chapter analyses the embryological and sexual symbolism found within the annual mountain-entry ritual of Haguro Shugendo called the Autumn Peak (Akinomine), using both written sources and ritual procedures, together with the results of participant observation over fifteen years. It looks first at the embryological symbolism associated with the attire and accoutrements of the practitioners (shugenja), based mainly on a collection of Haguro kirigami (memos of ritual instructions) called the Hōgushū, collected in the seventeenth century. It then studies the meaning of the womb, intercourse and conception, the stages of gestation, and birth as they are defined and practiced in the ritual procedures of the Akinomine. Finally, it examines the sexual symbolism associated with the sacred places visited by shugenja in the latter stages of the Akinomine. These findings demonstrate that Haguro Shugendo consciously employed the sexual imagery and symbolism found within wider medieval esoteric discourse in Japan and adapted it to both physical action and to a ritual imaginaire intended to make shugenja experience the passage through death and rebirth, which was a precondition of their realising buddhahood in that very time and place (sokushin jōbutsu).