My Stepmother and Stepsisters Aren't Wicked

Student council president Mikuriya Sada valued discipline and, due to her strict personality, enjoyed immense support from the students. Though she suspected she might be mistaken, Miharu couldn't help but see the student council president's image in the woman with the dog she'd met in the park.
Meanwhile, in the student council room, a meeting was being held. The topic was the survey conducted on parent-teacher day. It concerned the negative impact and loss of social credibility caused by the enrollment of an illegitimate child, but for some reason, no such concerns had been raised by the parents of Kouzo Miharu's class…

It's the day of the school sports festival. As the student council provides commentary on the events, Sada and Marika face off in the short-distance race. Koyuki also puts up a good fight, but Miya and the Odama team are struggling, and the Rindo team takes the lead.
Then it's Miya's turn...
Determined to bring home victory no matter what, Miya takes part in the scavenger hunt. She spreads out the paper with the theme and runs off, only to find Marika and Arisa, who are also participating...
Despite Miya's efforts, the Odama team can't seem to close the gap in points. After eating Teru's special bento box, Miya is ready to go all out in the afternoon as well...

During summer vacation, Teru suggests they go to the beach. While Marika and Arisa are excited, Miya seems anxious due to past memories. Encouraged by Teru's words, and seeing the vast blue ocean, her apprehension dissipates...
There, they encounter Lil, Homare, and Takiko from the student council. Seeing Homare, Lil seems strange.
They all decide to head to Kouzo's villa together. After arriving at the villa, Miya and the others play on the beach. As usual, Marika and Arisa start fighting, and Homare tries to stop them...

Summer vacation is over, and the new school term begins today. Miyu has been absent from school due to illness. Lil and Koyuki are worried about Miyu. Arisa and Marika are also worried about Miyu.
Marika's eyes become sharp with worry, and seeing her like that, Arisa remembers the day Miyu first came to Kozou's house.
At the Kozou house, Teru and the others are nursing Miyu back to health. Miyu doesn't want to worry everyone, but she is delirious with fever.
In her hazy state of consciousness, she hears her mother's familiar voice calling her name—