The family pet of the Niwa family and Dark's familiar spirit, With responding to Dark's call no matter where he is and transforming into a black, winged creature that becomes Dark's wings by clinging to his back. He can also perform other transformations, and can turn into Dark or Daisuke, but is not very adept at communicating verbally. For example, With's attempt to say "Daisuke" comes out as "daisuki" (lit:I really like (you)). Wiz does not like learning new words as well.
With resembles a hybrid of a dog and a bunny (the closest animal Daisuke could compare it to was a lop-eared rabbit), and it is unknown how old With is. In this form, With normally says "Kyuu." He hates water, is afraid of scary movies, and hates Krad. In the English manga translation, With is known as "Wiz", or 'Wizzy.'
With is the Japanese version, Wiz being the English manga version.