Keroberos Tsukishiro, often affectionately referred to as Kero-chan, is a key character in the anime and manga series Cardcaptor Sakura. As the Guardian Beast of the Seal, Keroberos is responsible for protecting the Clow Cards and overseeing their chosen master, Sakura Kinomoto. In his small, plush toy-like form, he is cheerful, energetic, and loves sweets, especially pudding. Despite his cute appearance, Keroberos is wise and powerful, playing a crucial mentor and protector role throughout Sakura's magical journey.