This works depicts a child reaching out for sushi in Matsugasushi, the most renowned and luxurious sushi shop in Edo (the former name for Tokyo).
Hand-formed nigiri zushi (sushi) was developed in the early 19th century around the Bunsei era (1818–1830).
The sushi made by Sakaiya Matsugoro, whose shop is depicted in this image, was very popular at the time.