Mari, a lesbian sister who loves her younger sister Natsuko, who struggles with bedwetting. On the morning after Natsuko wets the bed, they enter into a forbidden incestuous lesbian relationship starting from the sister's comfort... Natsuko experiences her first excitement from her sister's cunnilingus and loses herself in squirting. Sisters drowning in debauched pleasure indulge in secret, erotic lesbian sex... The two cross the sisterly boundary and fall into incestuous lesbian lust...
