When Thanatos learned that Shizuka Uchiha possessed an inner world, one that had only just taken shape, greed and desire blinded him. All he could think about was how to steal it from her, and he completely forgot about Itachi Uchiha, who stood nearby, watching for an opening. Seeing that the inner world had consumed all of Thanatos's attention, Itachi and Shizuka put their heads together and decided that she would act as bait while he gathered his power to unleash the full strength of the Ame-no-Murakumo.
That was why Shizuka had been stubbornly holding out against Thanatos. Given her strength, if Thanatos had regained even a sliver of reason, he would never have let Shizuka, who was still in the mortal realm, lead him around by the nose.
Unfortunately, there were no second chances. Completely blinded by his own desires, Thanatos could no longer see the situation clearly. After pouring all his chakra and ocular power into the Ame-no-Murakumo, Itachi had been ready to strike. But fearing that even this would not kill Thanatos, he poured all the power of the Yasaka Magatama and the Yata Mirror into the sword as well. The Ame-no-Murakumo now held all of Itachi's chakra and ocular power, along with the power of the Yata Mirror and the Yasaka Magatama, treasures of the same rank.
The Ame-no-Murakumo had now fully regained its former power. Only the instant its strength was completely unleashed did Thanatos snap out of his trance, but by then it was too late. Shizuka had used the power of her inner world to trick him, then gathered the entire world's strength to bind him. Though the restraint lasted only half a second, that was enough for Itachi to unleash the Ame-no-Murakumo's strongest strike.
A streak of red-and-white sword energy shot from