In the 8th and final year of the game after the second semester, Akizuki may propose to your daughter while they are on a date. In order for this to happen, Akizuki's orb level must be at its absolute highest and Akizuki's friendship event must've occoured. Also, you must not have triggered any other endings. If you accept the proposal, the two will marry at the end of the game.
In order to meet Akizuki, your daughter must have accepted Mouri's scouting event. You can get scouted by Mouri by going to town with charm over 300 after entering junior high (if playing untranslated, choose the top answer to accept Mouri's offer).
There are two different endings that one can achieve when marrying Akizuki, a good one and a bad one. One achieves the good ending by having low independence (under 80), and the bad ending by having high independence (80 and over)
In this ending, your daughter gives up her career as an actress to support Akizuki. They suffer some friction in their marriage, but they manage to overcome it. They have three children.
After the marriage, Akizuki disapproves of the places your daughter has been visiting as it does not give "a good image" for them. After fighting, they divorce.
3 1/2 stars.