the game is not finished. i'm not sure exactly what you mean by "this part" but you can purchase the whole game for $20 which gives you two routes as the devs are MIA and refusing to explain what the situation is in regards to where the rest of the routes are OR you can individually purchase the two routes that are released (hayato and mikio) for $5 a pop.
so no, if you purchase this game you will not get the full story. we have not received an update about the game in well over a year so its up to you if you'd like to spend the money but its looking like this game is abandoned and all we're getting are the two routes.