Chrono Crusade

Chrono Crusade, originally known in Japan as Chrno Crusade (Japanese: クロノ クルセイド Hepburn: Kurono Kuruseido), due to a typo, is a Japanese manga series written and illustrated by Daisuke Moriyama.

Set in New York during the 1920s, Chrono Crusade follows the story of Rosette Christopher, and her demon partner Chrono. As members of the Magdalene Order, they travel around the country eliminating demonic threats to society, while Rosette searches for her lost brother Joshua.

"Temptation" (Poison) (Episode 20)
Aion asks Rosette to join his side in order to save the inhabitants of the San Francisco. Rosette agrees to his proposition, but she still wears the soul timepiece as a reminder for her life.