it appears that ayane wants to remake what happen 10 years ago to happen...
shin was still in his dream, to be accurate in the "whale"... but then when his friend are fighting ayane... he realize something... he has the choice either to choose to be with his brother, and Jun/Yuki or his friends fighting to prevent history happens again... causing all the destruction..
Shin chose to fight and prevent the history happens though ryou(he managed to calm the whale down) trying to convince shin that this time will be different. But he still fight and prevented it... I was pretty shock when ryou let shin to prevent jun/yuki to become one with ayane. However, it is said that the persona bring misfortune or abuse as a tool for war.Persona are distortions. Shin went berserk and trying to cut all the link with the whale. Ryou assisted shin in it and they put an end to it. Things went back to normal but unforunately... Ryou was seriously injured(to be accurate killed by his persona). And shin realize the truth about the ending story for the feather of the whale was the opposite from the book.