Shin Mahouka Koukou no Rettousei: Cygnus no Otome-tachi

The series moves away from the Shibas and focuses on Alisa Iba, now Alisa Juumonji, the half-sister of Katsuto Juumonji, who came about due to their father having an affair before remarrying after the death of his first wife.

(Source: Mahouka Koukou no Rettousei Wiki)