Not Sheela na gig related but should prove a fascinating read
Well known expert in Japanese Studies Dr Stephen Turnbull, has released a new book called Japan’s Sexual Gods Shrines, Roles and Rituals of Procreation and Protection.
Japanese shrines have many deities represented by phalluses and female sexual objects. This book provides a gallery of photographs and locations along with details of their rituals, festivals.
There is also a YouTube channel which has a number of videos relating to the book
The book on Amazon