My Girlfriend's Mom Sumika Hatori (2009)

Sumika Hatori is a stepmother who finds herself in a compromising situation with her stepson Ryo-kun. She is a mature woman who takes advantage of her stepson's youth and naivety, engaging in a taboo stepmother-stepson relationship. The central kink of this movie revolves around the forbidden and secretive nature of their interactions, exploring the complexities of their familial bond and the power dynamics at play.