Oshizushi is the name of a unique sushi variety, distinguished by its signature rectangular shape. Also known as pressed or box sushi, it is made with oshibako, a long rectangular wooden appliance which acts as a frame.

It incorporates vinegar rice and is topped with various seafood ingredients and condiments, neatly layered in the oshibako, then compressed, creating a firm block of sushi which is subsequently cut into bite-sized pieces and served. Originally, the name was used to refer to an ancient preservation method in which fish was placed in similar containers alongside fermented rice.

Over time, with the development of vinegar rice, the method was perfected in Osaka in order to create the sophisticated oshizushi which we know today. Traditionally, it employs marinated or grilled seafood ingredients such as eel or mackerel, but the varieties which employ raw fish are also quite common.

The unique preparation method allows the creation of exceptionally complex versions of oshizushi, which can consist of many layers or may have detailed and comprehensive creations on top of each individual piece. Nowadays, it is still associated with the region of Osaka, where it is commonly found in numerous sushi restaurants. Due to its distinctive shape, oshizushi is easily transported and has become one of the most convenient sushi varieties offered as a take-out dish.