Line the mold with the oil.

Combine warm water with instant coffee. Mix it until the coffee dissolves. Wait until it cools.

Combine water + coffee with katakuriko, sugar, and vanilla extract in a pan.

Use low heat. Continue stirring until the mixture becomes thick, a bit translucent, and can be lifted with the spatula.

Put it on the oiled mold. When it is cool, store it in the fridge before slicing it.

My kids eat this with whipped cream. But I think it is also tasty without anything else.