I spent a lot of time writing, and i forgot some tips and theories, haha...
- It was not made clear WHEN Iwabuchi found Rika after she got married. However, considering Miyabi's take of favoritism torwards Momonga, he's been basically boosting Rika since the beginning;
- The shadow guy from chapter 1 is probably just a placeholder for a possible plot twist...that turned out to be just a mole from Iwabuchi, and possibily the mole who kept watch over Rika all this time( his dialogue about Sousuke bringing donuts to Shingo got no answer, so probably even Iwabuchi was pissed at this "lover" thing and got pissed). However, this shed to me some light into Suguru Terauchi's character: i'm assuming he's just another mole of Iwabuchi, this time to keep track on Sousuke. And since Iwabuchi boosted Momonga to top account, showing to him that his wife was having an affair was going to be a dealbreaker for their marriage, and consequently, Make Rika rush back to Iwabuchi;
- This also spirals back to chapter 10, where Rika says "thanks to him, i can have a little more fun". She's talking about Shingo. Mainly, how he made possible 2 things: test Sousuke's take on adultery for her "true love"plan...and keeping getting boosted by Iwabuchi, earning more money. The first is proven throughout the story, but the second makes sense now, as she's clearly aware Iwabuchi caught her again, by looking at her bank account and seeing how unnaturally it grew;
- Rika, as a character, has 2 main flaws.
To the story( as Sosuke said about 2 to 3 times now), she treats others as inferior to her. Predictable. And even as she says it, in the end, she was outdone by Sousuke, who was the most predictable and manageable of the roster, but grew enough to break the way she predicts him, and delivered a surprise outcome.
To the readers, Rika being cunning beyond factual understanding just sounded like a ridiculous plot device, until it turned into a dual-edged knife. On one side, she planned every possible situation, including her escape, and even trapping Misato on the go, and the fall of Shingo and Iwabuchi. On the other, blame her narcisism to being catch by Sousuke and trying pathetic excuses, with shallow thinking and a sudden personality shift that would amount to nothing, even by her standards;
- That's why i can't bring myself to see the story end on chapter 108. Rika has been so cunning, so smart, and suddenly, being cornered, she sounded so pathetic...it's not that i don't want the story to end, but as we're now, it's going to be about, 2 to 3 chapters of flashback about her, an epilogue of sorts, with Sousuke coming to terms with everyone, the outcome for everyone else...and probably, Sousuke becoming a vigilante of sorts, helping out against adulterous people, with Akiba on his side, wanting to see other people have sex.