This video introduces a recipe for water yokan (a type of Japanese jelly) that can be made in a milk carton using only three ingredients. Its key feature is that it can be easily made using a microwave, without the need for molds or pots. Simply heat water and agar powder in the microwave, mix with strained bean paste, pour into a milk carton, and chill in the refrigerator until firm. The result is a smooth and elegant water yokan. This refreshing summer treat is perfect for beginners in Japanese confectionery making.