Yume Nikki ~Tooi Sora no Shita de~

Main character gets a part-time job to tutor the daughter of a famous fashion designer. But his employer dies and arrangement is cancelled. However, he's approached by the second wife of the deceased man asking to insult and train deceased man's daughter in order to sell her to a wealthy house. It goes contrary to main character's ethics, but when he sees the innocent smile and gentle manners of the girl, he already knows the answer: "I'd like to insult a girl like this ..."

[From vndbreview]