I've been wondering about Miyu and Shishijima for a while - sure, he's overbearing and she's said she despises him, but she does seem to take special pains to trash-talk him, even AFTER SHE DECIDES TO SPLIT OFF IN GROUP WITH HIM. She also seems to have issues with men in general. i'm frankly just waiting for her to have a psychotic break and Lorena Bobbitt one of the boys. 😖
As for Chiyo and Igarashi - feth it, he clearly wants to avoid a conflict here, so whatever. Tactically speaking, it's better this way, as there is at least one other witness to Ookuma's duplicity, and everyone has noticed how Igarashi has been taking pains to defer to Chiyo and the group's harmony.