If you do a "gotsun" with your fist, you'll be instantly chilled! I found a product called "Instant Cooling Pack" at Daiso, a 100-yen shop.
A cooling pack with a size of approximately 180 mm x 110 mm. The materials are ammonium nitrate, silica gel, and water. When the water bag inside is smashed with a fist, a reaction occurs and the whole cools at once. If you apply this to your forehead or nape, you can enjoy a pleasant coldness. Condensation is likely to occur, so it is recommended to wrap it with a handkerchief.
There is a water bag inside
When you hit it with your fist,
The water spreads inside and a reaction occurs,
The whole thing is chilly
After an hour, the feeling of tingling will fade, but the "instant cooling pack" is easy to carry without freezing. How about using it for outdoor activities and sleepless nights? The price is 108 yen (tax included) for one piece.