BOKU WA ONEE-CHAN NO OMOCHA

Boku wa Onee-chan no Omocha summary:

A special collaboration between Yoshida Morohe and Yuzuki Ryouta… a gyaru older step-sister and a younger step-brother with communication apprehension!!
Aonuma Aira is a 13-year-old with no romantic or friendly relationships. But one day, due to his parent's remarriage, the high-schooler Misa becomes his step-sister! She's a completely unknown entity to him, and gets way too close way too fast.
Moreover, her hobby is… makeovers? So she starts making him over until he's turned into a pretty girl!
What's in store for him after he's become his step-sister's plaything?