The Fading Life Tsubasa kuronikuru : Season 1 Episode 23

Seishirō attacks Fay after he asks if Kurogane and Syaoran live there. It is revealed that Seishirō gave his right eye to Yūko to obtain the power to travel between dimensions but unlike Mokona he can only use this power a limited number of times. Fay gets cornered and is defeated. Seishirō uses Sakura's feather and the people in the world start disintegrating like a computer program. When Syaoran and Kurogane get back to The Cat's Eye they find out that Fay was defeated by an Oni and that Sakura may have been taken captive. When Syaoran finds Seishirō and asks him what happened to Fay, he tells him that he killed Fay. Seishirō stabs Syaoran in the chest with a weapon made from Oni. Syaoran starts disappearing but then Sakura comes running out and hugs him and they both disappear.