Black Thunder AI recreates the crunch Oda Nobunaga would have made eating its bar

Black Thunder is the crunchy chocolate bar Yuraku Seika has sold since 1994, known for a signature 'ZakuZaku' (crunchy-crunchy) texture. When the brand turned 30 in 2024, the company ran '30 no Rakurai' — thirty projects intended to deliver lightning-grade fun across the anniversary year. Because March 9 reads as 'zaku' in Japanese, the brand used that date to stage a sound-based idea: make people hear that 'ZakuZaku means Black Thunder'.

The idea answered a question nobody had asked: what would Oda Nobunaga — the warlord famous for sweets — sound like biting a Black Thunder bar? Hakuhodo built a custom 'Black Thunder ZakuZaku AI' trained on the chewing sounds and facial images of 100 people. The AI learned how skull structure shapes chewing tone, then combined data from subjects whose features resembled Nobunaga's sharp jaw, high nose and prominent cheekbones to synthesize his crunch. Dentist Kōsuke Nakano reviewed the output and confirmed the high, resonant sound matched what that skeleton would predict.

The recreated sound became the campaign itself: a short film released March 6, 2025 on Black Thunder's official YouTube channel and kept online until the end of August, plus an audio advertisement streamed on Spotify for one week, both tied into the anniversary project site. Instead of claiming crunchiness in a picture, the brand let people listen to a famous sweet tooth enjoy the bar — a premise built for curiosity and sharing.

The work was recognized at the 65th ACC TOKYO CREATIVITY AWARDS 2025 with a Bronze in the Radio & Audio Advertising category (Audio Execution) and a Craft Award for its planning, with Hakuhodo credited as agency. Japanese tech and PR media covered the stunt as an example of sound-based branding powered by generative AI, showing how a texture claim could become an audio property worth talking about.