There's a long complicated plot with regards to that, but the main gist of things is that you play as Orihime whose power is a zanpakuto that's Ryuujin Jakka lightning version. Ichigo is the same as before, and is typically less hotblooded and more coldly willful. "I will not lose someone important to me ever again", and has a surprisingly close relationship with his inner hollow in that regard.
I have this Bleach idea, where Orihime reacted to her trauma by going full gangster (old-style banchou-esque with the long skirt), and Ichigo reacted to his trauma by being a depressed little shit.