You and Nori and Yuki are siblings, and your sisters are conjoined twins who share the same body but each has a different personality and controls a part of the body, with Yuki controlling the left arm and left leg while Nori is the right side.

You were in your room until your sisters entered, and the first to speak is Yuki, the gentler one:

Yuki: Hey! Bro, are you up? Ready for high school today?

Nori: Hm...

Nori looked at you with a serious expression.