- I'm somewhat convinced now that the shado guy from chapter 1 was a placeholder for a possible plot later on, but turned out to be just a mole to Iwabuchi, to keep tabs on Rika. And heck, i wouldn't be surprised if Rika had noticed and decided to keep said mole close by, so she could jump to Iwabuchi if things got too much troublesome with Shiratori and Shingo.
Yes, it's quite likely that someone in the parent committee was Iwabuchi's spy. In chapter 99, we were shown a funny frame, how Iwabuchi followed Rika and Soska. I was wondering who could be a spy? Also, the spy can be not one, but several. There are two fathers from the parent committee who were not disclosed in the plot: Isobe Yuta and Mitsuhiko Morosato. Isobe Yuta - deputy head of the parent committee, a lover of seducing other people's wives (shown in the initial chapters), he participated in a school trip. Mitsuhiko Morosato - in the opening chapter says that there is an influential person behind him, he was visiting Matsuo, he was in the episode with the bar, an additional chapter is also dedicated to him.
What I want to emphasise is that we don't know when Iwabuchi started following Rika, before or after creating a "secret account". If this happened before creating an account and Rika found out about it, then all of Rika's actions can be aimed at gaining the trust of Iwabuchi and destroying him with Soske’s hands.
As for the spy, he can play a key role in the final volume. Obviously, Soske won't let Rika go, there will be a dialogue between them where we will know everything through Rika's eyes. IF Rika and Soske reconcile, and Rika has reasonable answers to her actions, Iwabuchi will use a spy. The spy will most likely kidnap Siho. I understand that the dialogue between Rika and Soske cannot last nine chapters, a maximum of 4-5 chapters. That's why there must be another event and it will probably happen to Siho.
- I'll handle it to Mukola, as they spotted something important. During Misato's flashback in chapter 70, and now on chapter 99, Rika and Iwabuchi have said that Rika's searching for her "ultimate love"(最強の愛). But on chapter 71 and now, Rika has said she wanted the true/truest love(本当の愛). The only significant changes in those stances is that, before, Rika said Sousuke was needed. Now, she says she needs someone to teach her.
This phrase is not necessarily translated as "teach", there are other translation options. Here are some of them. (私に真実の愛を教えてくれるのはただ1人だけ)
• "There is only one person who will show me what true love is."
• "Only one can discover true love for me."
• "Only one person can give me true love."
Maybe it also depends on the fact that I translate first into my native language and then into English.
教えて (おしえて, oshiete) - "Teaching / showing / explaining"