Understanding what mirin substitutes to use is essential for replicating Japanese dishes when you can’t find this sweet rice wine.
Made from rice, mirin is a sweet cooking wine that is a staple of Japanese cuisine. Mirin is similar to sake, although it is sweeter and less alcoholic, with a syrupy texture. It is used in many dishes from Japan, including teriyaki, ramen, and other noodle soups, and many sauces.
Best Mirin Substitutes
Mirin gives dishes a sweet, slightly acidic umami flavor that is quite distinctive. While this rice wine can be found in many specialty Asian markets, mirin substitutes are useful for those who don’t have regular access to that type of shop. It is not a commonly-stocked item in regular supermarkets. The lack of availability may require the use of a replacement in Japanese and fusion-inspired recipes. For a good mirin substitute, you can add sugar to vermouth, sherry, sweet Marsala, or white wine, among others. Additionally, mirin will need to be replaced by those who wish to avoid consuming alcohol. While it is difficult to replicate the flavor exactly, there are many easy mirin substitutes available. 
Many wine and liquor stores will carry at least one variety of this rice wine, which is very similar in flavor to mirin. Add a bit of sugar if using a dry variety. Sake is an alcoholic beverage that may be stronger than this cooking wine, so use it in moderation. 
This Italian cooking wine has a somewhat different flavor, but the acidity and sweetness are close to mirin, and it is more commercially available. This should be available in the majority of liquor stores and wine shops.
Any variety will make a reasonable replacement for mirin. Again, if it is a dry type of wine, mix in a small amount of sugar or other sweeteners.
For a rice wine-type flavor without the wine, substitute this more commonly available vinegar. Add a sweetener to more closely replicate the taste profile of mirin, or the acidity of the vinegar may change the taste of the final dish. 
Water and Sugar
The flavor will be blander compared to mirin, but a mix of 3 parts water to 1 part sugar is an easy solution. This substitute also eliminates alcohol from the dish if that is something you wish to avoid.