She resembles a black penguin with a white stomach. She has a pink bill and two red appendages on her head that may be ears or hair.
She's very quiet and thoughtful, and her hobbies are reading and composing Japanese poetry. Those poems are the kind that really gets to a girl-tam's heart, and they're quite popular among the Mesutchi! Her writings are very popular and heartwarming.
On Virtual Pets
Billkotchi is a TMP2 adult who evolves from Pirorintchi with average care or better. Marrying her to any TMP2 adult (Hiratchi, Marumimitchi or Billotchi) will result in PuchiChocotchi being born, while marrying ChoMametchi will result in Kakutchi being born, and marrying Kabutchi may result in either a pair of Kakutchi or PuchiChocotchi being born. Marrying any TMP1 adult will result in Kuritchi being born. It sleeps from 11 PM to 11 AM if it was neglected at teen stage or underwent a TMP degeneration; or from 10 PM to 9 AM otherwise.
Her name is a combination of the English word "bill", which means the beak of a bird, and ko, meaning "girl".