From https://www.pixiv.net/en/artworks/129858985

Post description by the original artist:
"Together, Buddhism and Taoism have conquered Shinto! Their opposing mikos, Reimu and Sanae, experience some bonding time atop their new masters' rods, joined at the nipple... and with Reimu riding Sanae's own rod, as well.
For today's credit, the choice is very very easy. While I'd love to say I'm responsible for the intricate patterns at the end, they are sadly beyond my ability. With permission, I have copied them from https://www.pixiv.net/en/artworks/122481271 (and may use some of the others there, later)."

[https://www.pixiv.net/en/artworks/122481271 has several womb tattoo designs made by "Azoth_the_Devil", including the Byakuren-themed one used here; all womb tattoo designs, including some posted on Azoth_the_Devil's Twitter account and not included on the aforementioned Pixiv post, are available at the following E-Hentai gallery: https://e-hentai.org/g/3930907/4ec77d2a76/]