It just hit me, you know what would be seriously fucked up?
We know that Maria knew Shizuka from when they were younger
What if Shizuka and Taiichirou went to the same school as her and Shizuka bullied Maria to keep them apart, tried to have her incriminated in uni to get her out of the way, followed Taiichirou like a stalker when he joined the force, and coerced Taijou to cover up the murder of his son as revenge or in the hopes that it would make them divorce
Like, maybe she wasn't even taking pictures of Okaya at the beach, but rather of Taiichirou surfing
Yes, I know it's a massive stretch, but it's far from the biggest plot twist we've had