The storylines for this game differ greatly from those of "Samurai Warriors 4," in that they focus on the individual characters themselves, rather than the regional conflicts and overarching plot to unite the land featured in the previous game.
Stages unlocked within Story Mode can be played in Free Mode, using any character of your own choosing.
You can also play both Story Mode and Free Mode together with another person online, although you will be unable to use the character switching feature found in the single player game.