So he just wanted to prank his younger brother to feel the same way as he felt, like for just a moment?? It's…
His daughter is 100% clean during that scene, but his wife's face is a bit messy. either the music box trigger a bomb that placed somewhere in the recital (i assume somewhere near their seat) or it's a "prank".
I honestly expect more gore, this one is still mild to low. Also the tonal shift feels a bit rushed since Morita is absent from the first half of the film, should've put Wagu's flashback right before the scene where Morita watch Okada from distance. It's not as bad as MDL rating, deserve somewhere between 7.5-8.