If you have no time to make homemade sushi vinegar (寿司酢) to season your steamed rice (for making sushi), you can purchase seasoned rice vinegar or sushi seasoning (寿司酢) at Japanese/Asian grocery stores. It’s a quite convenient condiment to have in your refrigerator if you frequently make sushi at home.
However, I still prefer making my own sushi vinegar/sushi seasonings from scratch when I make sushi rice. Click here for the recipe.