Usa-chan in the anime, is a stuffed pink rabbit that belongs to Honey. His favorite, late grandmother made it for him long ago, and it is one of his most treasured posessions.
One episode reveals just how important Usa-chan is to Honey when the doll is accidentally stained, causing the host club to panic, mostly because of a myth about Honey that Tamaki told.
Usa-chan is also alive in the Haruhi in Wonderland! episode. In that episode he is supposed to be the White Rabbit with a waistcoat and a pocket watch.