All of the pictures above is one of the characters from this book, his name is Kai. He is the funny one out of the two and makes jokes all the time.
These pictures below are of the character named Yori, he and Kai do almost everything together and sometimes he feels like Kais' babysitter. He also wears different colored contacts a lot, so his eye color switches.
Now you know who the two main characters are, ENJOY THE BOOK!!!
BTW I DO NOT OWN THESE PICTURES, CREDIT TO THE OWNERS!