The plot thickens if page 22 means what I suspect - had that feeling from day 1, that it might be him committing all those atrocities (when we first saw the dead cat) and his mom is just covering for him/shielding/gas-lighting him from reality.
I'd say the boy was manipulated so much he's so confused. At this point in time, he has no one. The father is not really here for him and the mother is in prison, MC is probably so stressed, his future so uncertain.
The great thing is the "Don't do it... Stop..." could apply to two things:
The past - Don't kill that cat/push your cousin down the Grand Canyon/beat up your awesome hairstylist.
OR
The present - Don't tell the Po-po nothing! (since she already confessed, maybe not to break and self-incriminate himself).
The police does not know that seichi has mental trauma other wise they wouldn't do this.
As long as seichi can deal with it, this will help him break away from her mental hold on him.
idk much about Japan law but I highly doubt they'd put a kid through this kind of trauma lol.
iirc american law wouldn;t separate the parent from a child for this kind of shit, especially if he wasn't even the suspect.
Two things: a: "Sei honey, don't do it. Let me Push him off for you." OR b: "Sei honey, don't do it." and he pushes him off. Sei saw all those butterflies the Moment it happened. They can also be interpreted as the corpseflies from the Dead Cat he probably killed. Symbolizing that he has a Blackout of the events he committed die to his Trauma. BUT there was never any Indikation what that Trauma is. Except from the Trauma his mom caused to him we saw during the manga.
Writing comments from a German phone in English with crappy autocorrection. Please keep the Typos that I made. Thx.