Since hiyayakko is all about the tofu, I recommend visiting a Japanese grocery store to look for a high quality silken or extra soft tofu. They have a bigger selection of tofu to choose from, plus, they can help you with choosing the best one.
Hiyayakko is a Japanese cold tofu dish that is served with various toppings. The word hiya means cold, and yakko were the servants of samurai. Those servants wore vests with crests called kuginuki-mon, with patterns that were square shaped. From there came the expression of cutting something into yakko.
Start by draining tofu and leave on a plate to let some of the excess water out.
Slice tofu into four equal blocks and place each in a small shallow bowl.
Top with favorite toppings, adding bonito flakes last.
Drizzle soy sauce or ponzu sauce and serve.