Lucky (ラッキー,Lucky?) is Nagi and Klaus's former dog that used to live in the garden at the Sanzenin mansion.
Lucky is a medium sized dog, He has brown and white fur and black eyes and is seen wearing a blue collar.
Lucky is first mentioned by Klaus, in his "normal story" to be a cross breed dog that also had some stupid characteristics, but would return to his dog house by 6 P.M. every evening. Until one day Lucky mysteriously disappeared causing Klaus to search frantically for him all night with no avail, But after three days much to Klaus's surprise Lucky mysteriously reappears in his dog house.
End of the World Arc
Lucky appears in a flashback in Chapter 183, grabbing Izumi's doll and chewing it up before attempting to attack her. Witnessing the situation, Hayate saves her by hitting him with a large stick.