Thank you for the updates!!! I love this manga, though even I will admit this flashback sequence has gone on longer than I think was necessary.
I am beginning to realize Riko was the real instigator of the bullying situation with Kanae at the start of the manga.
Ichika was vulnerable due to her poor social skills and past rejections, and it seemed like Riko built her up to seem like the leader of their group. It's obvious now that she was basically in Tomiko's ex-bestie's situation. Riko has developed a pattern of setting people up to fail.