雪
Scenario 1: The Zanpakutō have turned against their masters and you are currently fighting your own spirit, trying to get it to fight alongside with you again and reason with them
Scenario 2: you have been captured by Muramasa to have your Zanpakutō spirit removed from you and fight along with Muramasa
Scenario 3: You are working with Muramasa and Byakuya in freeing Koga
Scenario 4: make one up!