Pon, is Yellow. Zi is Blue:).
Pon and Zi are made by Jeff Thomas.
According to Wikipedia, Jeff Thomas (the creator) did not want to determine their sexes. Thomas wanted to avoid sex-determining his characters since his goal is that everyone should be able to recognize themselves as Pon and Zi. They may be two guys, two girls or maybe a guy and a girl, that is why many will recognize themselves in one Pon and Zi picture.
"pon" and "zee"
'Pon and Zi' were created in 2004 by Jeff Thomas .
Pon (yellow) and Zi (blue) ~ see related links below .
Pon and Zi are characters created by artist Jeff Thomas. Pon is a blue rabbit and Zi is an emotionless, pink-skinned entity. They are often featured in illustrations that depict themes of love, friendship, and emotions.
Pon is the yellow one and Zi is the blue one.
Actually, the author, Jeff, states that Pon and Zi don't have a specific gender for them because both female and male genders seem to connect with Pon and Zi.
at Amazon
Pon & Zi were created to be 'gender-less'. The creator wanted them to be applicable to any relationship, whether heterosexual or homosexual.
there isn't a book st the moment but if you look pon and zi up you can go to the makers site and help fund the making of the book