おしかけおさなづま3(3乗）

Main character is a high school student who lives alone after losing parents in a traffic accident. He finally regains joyfulness supported by his aunt, childhood friend and classmates. One day an he is visited by and old man claiming to be his grandfather and owner of a huge conglomerate. In order for protagonist to inherit this business, he needs to marry first. Grandfather chooses a bride candidate to live together in one house. However, protagonist's friends rebel against this decision, so three more girls join them. Thus, a lively cohabitation of five people begins.

[From vndbreview]