The Haunted Bookstore, book 1: Gateway to a Parallel Universe
Shinobumaru et Munashichi2019

Kaori lives in an otherworldly bookstore with her adoptive father. Together, they provide books to the strange denizens of the spirit realm. But Kaori's peaceful days come to an end when she rescues an injured boy from the streets--a human, like her, from the mortal realm. The boy's name is Suimei, and he's an exorcist, the natural enemy of all spirits. Can Kaori convince Suimei that the line between human and spirit is far hazier than he thinks?