It's the BULLYING that Eiji kept secret from her along with only finding out LATER about everything from the teacher as they gather the evidence! Kondo and Miyuki are IDIOTS for being SO FUCKING PUBLIC since guess what
A Foodie Streamer was nearby that night in chapter 1, heard Kondo's loud fucking mouth among the other commotion and had his camera on the trio! No words were heard, however the video CLEARLY shows next to Kondo "HITTING" Eiji unwarrented, proving he LIED about laying a hand on him along with Miyuki also exposed as lying cause GUESS WHAT! Eiji never grabbed her on her wrist....KONDO DID as the video showed, meaning his "I didn't see or no nothing" is also proven a lie!
Seeing her son's "humilation" and be HARMED, and ALL because Miyuki had to be a Slut! Ms. Aono.....REGRETS letting Miyuki off with a "Stay away from my family" earlier and wished she had STRANGLED her instead back then! Next to the Fact the Teacher gets a copy of the Stream, which goes on among MANY OTHER THINGS leading to the EXPLUSIONS of Miyuki and Kondo! As others said previously! Miyuki SQUANDERED her last chance to tell the truth, and not even for KONDO, because SHE was scared of losing her reptuation, and acknowledging later that losing Eiji meant that REPUTATION was pointless so she wrecked his life to save ONLY HERSELF! Just another level of her SELFISHNESS
But Ms. Aono, on Eiji's behalf as his mother and Guardian, she files a police report and plans on SUEING BOTH KONDO AND MIYUKI! Over the assault back in chapter 1 in Kondo's case, and the Slander and Conspiracy in Miyuki and ESPECIALLY Kondo's case! THIS leads to the police following up, and Kondo like the LOSER COWARDLY SMUG SNAKE THAT HE IS "Running away" when they show up at the school for him and getting his ass arrested cause THEY ONLY CAME TO QUESTION HIM! If he had kept his cool, they'd have left after questioning him and that would be it, but well a DATE later with Miyuki that I think is UPCOMING here in the Manga will SHOW "Just how BRAVE Kondo is when things aren't working in his favor! He's smug because of a sense of invincibility, but show A CHINK and he will panic and show how much of a LOSER he really is) This just starts the FUSE on disproving the lie that Kondo was "a big hero who protected Miyuki from her creepy EX BF Eiji" since seeing him being carted off
The Second INTERVIEW and Miyuki panicking when questioned by the other students WHY she's being called back in and begging forgiveness is the DEATH KNELL as now EVERYONE IN HER CLASS and the SCHOOL EVENTUALLY discover she and Kondo CONSPIRED against Eiji and LIED, Eiji wasn't the "creepy Ex BF Stalker" he became "The poor loyal BF who was betrayed by his GF who cheated on him, then to protecT HERSELF from expusured, CONSPIRED with Kondo to frame HIM as the bad guy!" While that's not 100% the truth as Miyuki was POINTLESSLY irrelevent once she choose to remain SILENT, which only WORSENS her REPUTATION LOSS as again, "keeping quiet" destroyed ANY CHANCE once the truth came out for her to save herself!
Kondo is lucky! Jail, Explusion and Juvie mean he doesn't have to SUFFER the effects of his reptuation loss and the students turning on him, ESPECIALLY the Soccer Club who get EXPELLED AND CLOSED DOWN for their part in helping Kondo by targeting Eiji for bullying! Not a single one is INNOCENT, especially the TEAM CAPTAIN who as you saw in HIS interview before Miyuki, "LIED" about noticing anything going on, INCLUDING how Kondo co-opt the Club Members into his personal minions because he SELFISHLY was focused on his "University Propsects that he COULDN'T MUSTER getting Kondo under control and LET him do as he pleases! He may not have been WORKING for Kondo, but his inactions and willful neglect was MORE then enough to AID in his corrupting the club for his wrong doings!" Suffice to say Kondo best never run into ANY of his FORMER PEONS as they made it CLEAR for ruining their future (even though it was STILL their choice to believe and follow Kondo's lead so equally their own faults) they plan to "bust him up if they ever see him!" And the loss of his FATHER'S STATUS AND MONEY and being a NOBODY NOW means Kondo's in for a WELL DESERVED BEATING SOME DAY!
But Miyuki isn't so lucky and has to deal with "what Eiji went through" only WORSE and WELL DESERVED that even SHE can't feel sorry for herself when she remembers she ABANDONED Eiji to this which he never deserved! She went from "innocent girl next door" to "A slut who will let ANYONE do her" (Not true as she only did it with Kondo, but well, what you'd expect!