To make it to the play even of man who is not playing the former work easily, it plainly introduces the flow and the highlight of the former work with OP. In that case, ED that makes one of the each heroine of the former work (three people in total) dark can be selected by the multi. System where work heroine before it is assigned to new fleet vowing vengeance of the former work heroine in the state of being caught by work heroine and the former battle fatigues before dark executive is made respectively exists in each route. The old heroine assigned to a new fleet aims at the explanation of the connection and the composition of the confrontation as a brainwash to tell the truth etc. along the route.
Source: ErogeShop