彼女は「発生」してすぐに二つの運命に出会った。一つは生涯の敵となる「犬」、そしてもう一つはその犬から救ってくれた一人の少年。
ケルベロスは自分が怖いものは他人も怖い筈だと信じて疑わず、威厳を出すために犬耳を装着した。そして少年との思い出は、胸の内に大切に秘めたのだった。

After springing into existence, she immediately had two fated encounters: first with a dog—a creature destined to become her arch-nemesis—and then with a boy who came to her rescue. Convinced that what's scary to her must also be scary to others, she dons dog ears in order to give herself a menacing aura. And as for the boy, she keeps the memory of their meeting safe in her heart.