Leo, a god of death, has been sent to save human souls at a small hospice called Okanoue Hospital. For this mission, he’s been granted a special form: one with four legs, a tail, and a keen sense of smell. Thanks to his canine assets, Leo can seek out patients at the hospice who are plagued by a lifetime of regret. With his endearingly wet nose and friendly, furry appearance, Leo eases patients into their next life, seeing them off from the quiet hillside hospital without the burden of lingering remorse. 犬の姿で地上に左遷…もとい派遣された死神・レオ。 古い洋館を改築して造られたホスピス『丘の上病院』に派遣されたレオは、そこで『未練』を抱えた患者たちと出会う。 死と直面してなお、死よりも受け入れがたい『過去』に囚われた者たちの呪縛を解くべく、犬の姿で奮闘するレオ。 戦中の悲恋、吸血鬼の風聞、そして陰惨な一家銃殺事件……。 レオを待ち受ける未練は、一軒の洋館を舞台に徐々に形を成していく──。