The secret behind why Prizmmy and Prism Mates disbanded

Telling the others

Mia backed away, too dumbfounded to speak. No words could come out of her mouth.

"Momona's.... Graduating?!!"
She said in a bare whisper.

"She told me just the other day. That's why she hasn't been seeing us these days. She can't face us knowing that she is going to graduate..."
"But why???"
"She's 12 this year and like Ayami, Mrs Aoki wants Momona to focus on studying for a special test which will have a great influence on her studies this year. That's why... She asked her to leave the group."
".........."
There was a long silence between the two. Until Mia finally broke the ice.
"We have to tell the others about this."
"I know, but how? If Momona graduates, you know what will happen, right?"
Mia went silent.
There was a long silence between the two.
"We have to tell the others, no matter how hard it is. We have to take responsibility on this incident as the two oldest in Prism Box, especially you, Reina."
Reina lowered her head. "I understand. Let's go see the others now. We've been gone for too long a time. The others must be worried."

Back in the dance room...

"Hey, what's taking Mia and Reina so long?" Mirei asked everyone.
"Now that you mention it, they've been gone for 15mins already," Hina said.
"I'm sure something must've happened to Reina and Mia is comforting her or something right now. Let's give them both a but more time." Karin said.
Despite her calm tone of voice, she herself was very worried. She was wondering if Reina's strange behavior that morning had anything to do with Momona's absence.
"Don't tell me..."

Just then, Mia and Reina walked into the room. The others turned to look at them and we're taken aback by their tear-stained faces. "Reina, Mia, what happened? Did something happen? Tell us!" Karin said worriedly. Reina choked back her tears.
"There's been a...change... Momona is...is... graduating."

Everyone gasped. Airi covered her mouth in shock. Karin's eyes widened. Her greatest fear had come true.

Mia continued: "As we all know, if one more member of Mates graduates, there will be an equal number of members in Prizmmy and Prism Mates... And Avex would never allow that... Which would lead to..."

The tension rose as all the members knew the answer.

"disbandment."