TV-Series
Description
Keroberos, almost universally called Kero or Kero-chan, is a central figure in the Cardcaptor Sakura series. He is one of two magical guardians created by the powerful sorcerer Clow Reed, with his specific duty being the "Beast of the Seal" who protects the Clow Cards and is entrusted with the authority to choose the candidate to become the next master of the cards. For an unknown but lengthy period, likely decades, Kero slumbered within the front cover of the Clow Book until its accidental opening by Sakura Kinomoto.

In his everyday form, Kero appears as a small, plush, orange-yellow, stuffed animal-like creature. This guise resembles a cross between a bear and a lion, complete with large ears and two small white wings, which allow him to fly. He typically lives a comfortable, domestic life in this small form, having taken up residence in a little bed inside the bottom drawer of Sakura's desk. His true form, which he can assume when sufficient magical power is available, is a dramatic contrast: a massive, winged, mane-less lion with tawny fur, enormous angelic white wings, and a metal chest plate adorned with rubies.

Kero's personality is a vibrant mix of contradictions. He is often bossy, demanding, loud, and prone to egotistical boasting, frequently obsessing over his own "coolness". He is also a shameless glutton with an overpowering love for sweets, including cake, cookies, chocolates, and takoyaki, and he can become genuinely upset or even intoxicated if he is denied a promised treat. His hobbies are thoroughly modern and indulgent, as he loves playing video games, watching television, and even enjoys being filmed and dressed up in costumes by Sakura's friend Tomoyo. Despite this childish and carefree exterior, Kero is remarkably intelligent and wise. He possesses extensive knowledge of Clow Reed, mysticism, and the specific attributes of each Clow Card, making him an invaluable source of information and strategy. He deeply dislikes sadness and loneliness, and his boisterous personality often serves as a distraction from serious matters, though he is not immune to worry, as demonstrated by his obsessive concern over the impending Final Judgment.

Within the story, Kero's primary role is that of a mentor and guide. After recognizing Sakura's latent magical potential, he appoints her as the Cardcaptor and bestows upon her the Sealing Wand, charging her with the mission to recapture the scattered Clow Cards. He acts as her first teacher, explaining the nature of the cards and how to use the wand. While he supports Sakura, his motivations are tied to his core duty as a guardian: to ensure the Clow Cards are secured and a worthy master is chosen. Unlike his fellow guardian Yue, who draws power from the moon and is dependent on his master's magical strength, Kero's power is derived from the sun, allowing him to generate his own energy. Because of this, he does not need to eat to survive, though he certainly enjoys doing so.

His key relationships are at the heart of the series. His bond with Sakura Kinomoto is the most significant. Although he can be critical and demanding with her, calling her out on her mistakes, he develops a genuine, deep care for her well-being and believes firmly in her potential. He becomes a loyal companion and a member of her household. With Tomoyo Daidouji, he shares a friendly relationship; Tomoyo is happy to provide him with sweets and costumes, and Kero, in turn, willingly participates in her filming sessions. His relationship with the other guardian, Yue, is complex; they are partners in their duty, but Kero's sun-based, boisterous nature is a stark contrast to Yue's moon-based, reserved demeanor. Notably, Kero has jurisdiction over the sun-aligned Clow Cards, particularly the elements of fire and earth, which are the only cards that can be used effectively against Yue.

In terms of development, Kero remains a constant presence throughout the series. He begins as a duty-bound guardian, asleep for ages, and awakens to find his charges scattered. As the story progresses, he transitions from a purely authoritative figure who appoints a cardcaptor to a true friend and trusted advisor to Sakura. After she successfully passes the Final Judgment and becomes the new Master of the Cards, Kero chooses to remain with her as a companion and protector, solidifying his place as part of her family and not merely a magical servant. His respect for Sakura deepens as she grows into a powerful and compassionate magician in her own right.

Kero's notable abilities are directly tied to his sun-based magic. In his small, plush form, his powers are limited but include flight, a keen ability to sense other magical presences and Clow Cards, and, on occasion, the ability to breathe small fireballs. When he assumes his majestic true form, his full power is unleashed. He gains immense physical strength and can breathe powerful streams of fire. He also has jurisdiction over all Clow Cards associated with the sun, including fire and earth. This allows him to summon protective energy barriers and gives him command over cards such as The Firey, The Earthy, and even The Light. His true form is an awe-inspiring guardian beast, capable of immense destruction but used primarily for protection and judgment.