1960s --- Tokyo.

Shin is a boy who lived happily despite being poor, loses his mother who is his only family member, and falls into deep misfortune. Itsuki, a boy who saves Shin also lost his older sister. Those two boys are joined by Tae, a girl who can see youkai and together with Shin's guardian spirit Suu-san and new Youkai such as Nekomata, they take on a mysterious incident in order to retrieve the souls of their precious family! And what is the shocking truth that awaits them...!? An origin story for how Lord Enma became the rule of the Yomakai.

(Source: Wikipedia, edited)