On Tuesday, December 16, 1997 at 6:51 PM, roughly 4.6 million Japanese households watching episode 38 of Pokemon, Dennou Senshi Porygon, saw Pikachu’s thunderbolt trigger a red and blue strobe flickering at 12 hertz for four seconds. Within hours, 685 viewers had been taken to hospitals by ambulance, 208 required hospital care, and three arrived unconscious. This episode dissects the animation techniques called paka-paka and flash, the neurology of photic driving, and why alternating deep red and blue at that frequency overwhelmed the visual cortex.

We separate genuine photosensitive seizures from mass psychogenic illness, including an estimated 12,000 mild cases and a three-year follow-up showing most severely affected patients had never had a seizure before. We then follow the corporate fallout: TV Tokyo’s apology and four-month hiatus, police interrogation of producers, VHS tapes pulled from rental shelves, Nintendo’s stock dropping 400 yen, and president Hiroshi Yamauchi’s firewall argument that a monochrome Game Boy could not produce red and blue flashes. Finally we cover the worldwide ban on the episode, the blacklisting of Porygon from the anime despite Pikachu causing the explosion, the 4Kids scrubbing for the US launch, and the Harding test and flash guidelines that now govern global broadcasting.

• Why 12 hertz sits squarely in the 10 to 30 hertz photosensitive danger zone
• The scrambled episode order and the problem inspection report that preceded the return
• The deleted 2020 tweet that read Porygon did nothing wrong
• Simpsons and South Park parodies and a Guinness World Record nobody wanted
• The three-flashes-per-second rule and automated luminance analysis born from the incident