[Kichijouji Kitashirou] I'm Mommy, While I'm My Son? (A-Shi No Ijouna Aijou) [desudesu]

A mother and her young son wake up trapped in each other's bodies, and the boy's mischievous excitement—"We're having sex, of course!"—quickly turns the bizarre swap into a steamy game. As he guides his bewildered mother through the unfamiliar sensations of her swapped anatomy, her ample breasts bounce while he eagerly explores the tight, hairy rear he now calls his own. Things escalate into rough anal penetration, with her gasping "YEP, THIS HOLE IS MEANT FOR FUCKING!" before they end on a cheeky note on a mat that reads "WELCOME," sealing this taboo role-reversal romp.