Starts off right where episode 232 ended with Muramasa confronting Ichigo Quick switch to some building near Sokyoku where Senbonzakura is watching the fight from a distance. Rurio-kujaku and Hozukimaru asks what he's doing but Senbonzakura blows them off. Rurui-Kujaku gets pissed but Hozukimaru tells him to let it go and they'll get their revenge soon enough.Rurio-Kujaku proceeds to get happy at the prospect of revenge for his nickname. Back to Ichigo. Despite the apparent reconcilliation between Rukia and Sode no Shirayuki, Shirayuki remains under Muramasa's control and retreats under his orders. Muramasa then says that Rukia was allowed to escape so that he could lure Ichigo to SS so he could liberate all zanpaktou spirits (no mention of Urahara and co or the Visored).
Ichigo demands that Muramasa takes the fight elsewhere and Muramasa concedes. Arriving at some generic location they fight for a bit before Muramasa blocks a Getsuga Tensho and seems to vanish. The world then seems to scramble, turn sideways and gravity goes funny, pinning Ichigo to the floor. Muramasa then appears above him and proceedes to remove Zangetsu. Ichigo and Zangetsu fight briefly though Ichigo's heart isn't in it and he gets Getsuga Tensho'd through a wall.
The scene changes to the 4th Division's hospital wing with Unohana and Isane looking after Komamura. Nemu is explaining the results of Mayuri's research into the problem (with flash backs to Mayuri who has removed his headset and chinpiece while working). Unohana agrees to let Mayuri get some data on her in exchange for regular updates on Mayuri's research. Isane is understandably worried.
When the smoke clears Ichigo is still standing but with his mask half on and laughing in Shirosaki's voice (think during his fight with Byakuya) and proceeds to even the fight up while Muramasa's reaction can be summed up as WTF! Zangetsu explains that it is 'another soul that dwells within him (Ichigo) and the fight starts to go badly. Zangetsu gets a few cuts in but they heal almost instantly and after a particularly nasty blow Ichigo transforms into a Hollow like he did when training with the Vizard. Ichigo finally regains control, declaring he won't let Shirosaki have his body, pulls the mask off and his ordinary body returns. He's pretty dazed and starts calling out for Zangetsu, collapses and the episode ends with Muramasa staring down at him.
Next episode preview has Muramasa in Ichigo's inner world facing down Shirosaki, quick shots of Zabimaru's female half and Renji. The dialogue has Ichigo asking why Zangetsu turned agaisnt him. Zangetsu-ossan replies that he got sick of the scenerey and wanted to see some trees and get out into nature. Ichigo promises to plant him a garden. ^_^
In summary, I think Muramasa has just ibitten off more than he can chew.