Miraroma: Miracle Romance Strawberry Scramble

The protagonist is happily living with his parents and his younger sister. One day a nun throngs into their house explaining that he is cursed because of the mirror he accidentally broke a day before. Apparently, the curse put the whole world into danger. The nun insist that he should be monitored 24/7 and will therefore start living in their house. So as to not to be a freeloader, the nun, who happens to be a super rich ojousama, put up a large sum of money which overjoyed and caused his parents to go into a around-the-world trip leaving behind their children. On the very next day, some more girls throng in for the very same reason. The cohabitation to save the world begins as he wave goodbye to peaceful life.

(Source: VNDB)