So, she purposedly lead him to houses where she knew people wouldn't talk openly to him? Even though they targeted neighbor( in this case, people very close to the house) and it still left the feeling of "something's wrong here" with Sousuke? That's a very good approach!Yes, this looks very realistic - I’ve been thinking about it myself.
However, an important point cannot be ruled out: who exactly they approach with their questions.
Sousuke is completely unfamiliar with this settlement. Misato, for example, could be leading him only to those streets or houses where people have an extremely limited understanding of the essence of the problem. Some of them may genuinely know nothing; others may be afraid not of the house itself or of Riki, but of the actions of their clients. In any case, Misato fulfilled her main role - she did not allow Sousuke to do this alone.
Misato accompanies him from the train car, and at the very end we see that she consciously takes a risk and mixes alcohol with the psychotropic substances already present in Sousuke’s bloodstream, which speaks to her extremely dangerous nature.
For poetic approach, however, i'm still with Sousuke on this one. If the entire town knew and wanted to hide the story, it would be simpler. I've been in small towns with one bad gossip, i think you know a story or two about this kind of thing, too. It takes years, decades, but as the old people who know the truth keeps dying, and the young people don't preserve said things( unless it's cultural), then the story dies too. But here, it's still alive and brings discomfort.
Which brings us to...if the story is still alive, why would Rika appear in the class reunion, knowing she was still hated by some people( who knows how many)? Is the entire class reunion just a fake excuse to lead Sousuke into trusting Misato, while she prepares her chance to blackmail him with the fake photo she's going to take? Is it one of Rika's goals to "taint" the entire town, avenging her family for how it "tainted" them, making it know that she will never forget nor forgive everyone here?