Oukyuu Yasoukyoku

In this game, you play the princess who suddenly lost her parents as well as brother in an accident. The queen could not give birth owing to health reasons after you and your twin brother were born. Your father had been worried should anything happen to him or your twin brother, Cain, the kingdom would fall into the hands of his brother’s family, whose aggressive and military-oriented attitude he disliked. As a result, your father secretly asked the royal doctor Sieg to create a clone of your brother. On the night of the accident, Sieg informed you of the clone and the problem with him – he was like a blank piece of paper, with neither memory nor personality. The only good thing about him was the fact that he had the potential to grow up. Since the king and queen already passed away, the responsibility of educating your new "brother" rested on your shoulder.

[Edited from Nekoanime’s Weblog]