Hiyayakko

 is a Japanese dish made with chilled tofu and toppings. 
Variety of toppings.
The choice of toppings on the tofu vary among households and restaurants, but a standard combination is chopped green onion with katsuobushi (dried skipjack tuna flakes) and soy sauce. Other toppings include:
History and background.
"Hiyayakko" is also known as "hiyakko" or "yakko-dōfu". "Hiya" means cold, and "yakko" refers to the servants of samurai during the Edo period in Japan. They wore a vest on which the "nail-puller crest" was attached, on the shoulders; therefore, cutting something (e.g. tofu) into cubes was called . "Hiyakkoi" or "hyakkoi", the Tokyo dialectal term equivalent to the standard Japanese , is also a possible etymology.
In the "Tofu Hyakuchin", it is said that "hiyayakko" is so well known that it needs no introduction.
In haiku, "hiyayakko" is a season word for summer. This is because tofu is often enjoyed cold in the summer, warm and boiled in a broth in the winter.