Mamagoto

Ryouta's parents passed away recently and he is now completely on his own. Luckily for him, his father and a friend had made a prior arrangement where their children would someday marry each other.

This arrangement allows Ryouta to become the heir of his father's friend's company; but in order to actually do that, he has to marry one of his father's friend's four daughters...

(Source: BakaBT)