Suzu is an orphan. Her childhood was so hard since other kids always bullied her. They said she’s weird for being able to see spirits.
When Shinkuro came, Suzu feels so happy. He is a samurai who destroy spirits. He taught Suzu how to control her power so she can use the spirits around her.
Suzu thinks he’s like a father. But, as samurai has to travel, Shinkuro left Suzu a flute. There’s a spirit live in that thing. He is a fox spirit who looks like Shinkuro. He is the one who protect Suzu whenever she faces danger.
The real Shinkuro is actually live in the flute and have to share consciousness with the fox spirit.
As you expected from Kyoko Hikawa Sensei, the plot is really sweet. There are already 4 volumes released in Japan now, and still ongoing. So, be patient.