Tuna-mayo is a simple tuna salad that consists of canned tuna and Japanese mayonnaise, and tuna-mayo rice bowl (ツナマヨ丼) is an easy donburi rice bowl dish with tuna-mayo placed on a bowl of steamed rice. Tuna-mayo is one of the most popular fillings for Onigiri rice balls sold at any convenience stores in Japan. Creamy yet a bit tangy and salty Japanese tuna salad goes really well with steamed rice, and the flavor combination of tuna, mayo, rice, and nori seaweed is somewhat addictive. While Tuna Mayo Onigiri can be an excellent grab-and-go lunch in Japan, sadly not everyone is lucky to have convenience stores that sell such Onigiri nearby (certainly not where we live in the U.S.)