[DeepL Translation - needs review] Volume 1 Introduction: On June 24, 1989, 21 people, including children, were poisoned to death at an elementary school in the village of Oto-Usu, Hokkaido. Twenty-eight years later, Sano's son, Shin Tamura, begins to investigate the possibility that his father, who has been sentenced to death but has consistently maintained his innocence, may have been falsely convicted of the crime. When Shin visits the crime scene, he is suddenly enveloped in a thick fog ...
Very Entertaining, but Empty
It's a very entertaining thriller to read, but it has no real depth to it.
As for Japanese, for a thriller/mystery manga it's not very hard, so it can be a good recommandation for N3~. There is some Hokkaidô dialect sprinkled here and there, but you'll get used to it very fast.