In the "Tsukuroiya" series:

Volume 1: Awai no Mori
Volume 2: Madoi no Tobira

Within the boundary separating one world from the next, “rips” in the fabric of space will occasionally form. These tears allow the two worlds to bleed into each other, and, if left unattended, may threaten the everyday lives of the people living nearby. To find and repair these distortions, a seamster named Rem travels around the world along with his companion, a mechanical doll in the shape of a small girl.