Days with My Stepsister, Vol. 1 (light Novel)

When his father remarries, Yuuta Asamura winds up sharing a roof with a brand-new stepsister, who is also the hottest girl in his grade! But Yuuta and his new sister, Saki Ayase, have no delusions—they both carry trauma from their parents' difficult divorces, and they agree to keep a respectful distance. As it turns out, however, the two have a lot in common, and slowly, cautiously, they grow closer. But is the emotion blooming between them simple admiration, familial love, or something more?

(Source: Yen Press)