The Testament of Sister New Devil

When a high schooler's eccentric father suddenly announces his remarriage, he gains two beautiful stepsisters overnight. However, his new siblings harbor a secret far grander and more dangerous than he could ever imagine, catapulting his ordinary life into a supernatural battleground he never knew existed. Now caught between his new family and forces vying for ultimate power, our protagonist must navigate a world of demons, pacts, and burgeoning feelings. He'll need to decide where his loyalties lie as he uncovers the truth behind his stepsisters' arrival and the looming threat that could shatter his newfound, albeit chaotic, domestic bliss.

✦ AI-drafted summary