Riviere to Inori no Kuni

In order to save the broken country, Riviere does not pray.

Lying on the street almost dead from starvation, McMillia is saved by Riviere, a woman of many mysteries who's called the "Unprayer," and ends up working under her.
The Ashen Witch who laid waste to a gambling den. A mysterious gentleman thief. A masked girl. A succubus playing favorites. Searching for the illegitimate child of a former princess. As an assistant to the Unprayer, McMillia’s busy days are about to begin!?

(Source: Majo no Tabitabi Wiki, Edited)

Note: In July 8, 2021, it was announced that the spin-off will receive a full reboot under a different title name and it will release on January 14, 2022.