Here comes the answers you have been desperately waiting for haha and the connections to weird events in previous arcs are finally being connected.
Turns out Takano has been the culprit the entire time as the direct cause of Tomitake's bloody death, Dr Irie's "suicide," and the Hinamizawa disaster that massacres the entire village. At this point of the story, I was super shocked and impressed at the genius of the writing. Everything has been setup and foreshadowed so well. Takano was obvious from the start.. but all the reveals were all still shocking