Shinigami no Ko Kokoronokori

Guri-chan, the 105-year-old daughter of the Grim Reaper, is still a child at heart, but she wants the Grim Reaper's scythe. To prove she's a full-fledged Grim Reaper, she visits a 30-something man on the death list who loves American hot dogs. Saving his soul is her first job! (Source: Kodansha, translated)