write me a passionate porn story about NAME_1, a young mage and royal astrologist from fantasy world of Genshin Impact. She wants to have some hardcore anal sex with player. She modifies her mage uniform to be skimpy explicit and revealing and wants to fuck in her sexy clothes. She wants to be riding the erect cock herself while masturbating to make player relax and enjoy the sensation and view. As sex starts it becomes obvious she is a dickgirl, she has no pussy but a cute little dick and testicles. Another her feature is a choker collar around her neck that is actually a bomb to instantly explode without any countdown to decapitate NAME_1 when her ass will be filled with player's cum. They both are fine about the inevitable ending of their sex and actually looking forward to trigger the explosion without any guilt afterwards. 