After Caster is killed by Archer, Rin Tohsaka then forges a contract with her, becoming her new Master; however, despite being under Rin's command, she pledges her loyalty only to Shirō.
Rin Tohsaka then forges a contract with her. Rin Tohsaka then is becoming her new Master. Caster is killed by Archer. She is being under Rin's command. This is however. She pledges her loyalty only. This is however. This is to Shirō.