Indelible Memory Tsubasa kuronikuru : Season 1 Episode 22

Syaoran starts remembering about Seishirō and that he was the one who taught Syaoran how to fight. Syaoran and Kurogane go to a tower full of Oni to get information on Seishirō. At the top of the tower they find out that Seishirō is not an Oni and that town hall is planning to eliminate him for interfering. They also find out that the highest level Oni is in the form of a human and can command all other Oni. Seishirō shows up at The Cat's Eye when only Fay and Sakura are there and asks Fay if Kurogane and Syaoran live there.