Just a Bully by Gina and Mercer Mayer (Very Good, 2003, Pbk, 24 pages, Golden Books)

Used in very good condition. ISBN 0307132005

When a vicious bully targets Little Sister, Little Critter sets out to defend her, making him the focus of the bully's nasty pranks, until Little Sister and Little Critter join forces to stand up for themselves. Original.