Peak shift Day inspired by a vending machine

April 10th is Peak Shift Day ピークシフトデー in Japan. It is a modern commemorative day created by Coca‑Cola Japan in 2013. The date comes from a wordplay on how 4/10 can be read as "shift"; "shi (4) futo(10)" in Japanese.

But the meaning behind it is rooted in a very real social need that emerged after the 2011 Great East Japan Earthquake: reducing electricity use during peak daytime hours. To support this shift, Coca‑Cola developed the world’s first peak‑shift vending machine, designed to cool its beverages at night, when the power grid has more capacity. Moreover, they drastically cut daytime electricity consumption. Reportedly, these machines can reduce summer daytime cooling power by up to 95% yet still keep drinks cold for up to 16 hours. 

The goal of the anniversary is simple: make energy‑saving something anyone can participate in, just by choosing a vending machine. More broadly, peak shifting encourages moving part of our electricity use from busy daytime periods to quieter nighttime hours.