Keishichou Sousa Ikka 9-Gakari Season 12

The chief for First Division 9th Sub-division has gone away on a special mission, and in his place, an old teacher of the section's coroner comes to visit. The team's first case this season involves a series of corpses found tied to scarecrows out in the middle of the field. A fourth corpse is found, which appears to be a suicide, but is the case really a suicide or just the surface of something more complicated?