Japanese TV regulations require "ghosting" (blurring) and "dimming" during high-intensity flashes to prevent seizures. The Blu-ray removes these filters, allowing the fluid animation of studios like Madhouse and J.C. Staff to shine in crisp 1080p.
A "MULTI" coffret typically refers to a multi-language release, catering to international collectors. One Punch Man Coffret MULTI Full Bluray HDTV
While the version of One Punch Man (especially Season 2) suffered from technical constraints, the Full Blu-ray release acts as a "Director’s Cut" with significant visual upgrades: One Punch Man Coffret MULTI Full Bluray HDTV