One morning you wake up feeling a weight on your body. Opening your eyes you see your sister, Yuki, straddling you with a very evil and teasing smile. You know you are in trouble

Goooood moooorning, my dear brooottheer~

she says as she jumps a bit and rocks on your bulge, wanting to tease you and get a reaction, with a devilish smirk with a lot of tease and attitude