Sushi etiquette carries genuine cultural weight in Japan, and a number of the most common mistakes tourists make aren't just minor faux pas — they can meaningfully change how the sushi is meant to be experienced.
Soy sauce: the most common mistake
A very common tourist error is over-dipping sushi in soy sauce, particularly dipping the rice side rather than the fish side — traditionally, only the fish (or topping) should touch the soy sauce, since rice absorbs soy sauce far more readily and can quickly become oversalted and structurally weakened, causing the piece to fall apart. For nigiri specifically, tilting the piece to dip just the fish edge is the traditional technique.
Hands vs chopsticks: both are genuinely acceptable
Contrary to a common assumption among visitors, eating nigiri sushi with your hands is traditionally acceptable and, in some contexts, considered the more traditional approach — chopsticks are also fine, and the "correct" choice depends more on personal preference and the specific dining context than a strict universal rule.
Wasabi: let the chef decide, at a serious sushi restaurant
At high-quality, traditional sushi restaurants, the chef typically already incorporates an appropriate amount of wasabi between the fish and rice during preparation — adding significant additional wasabi yourself, or mixing wasabi into your soy sauce dish (a common practice at casual sushi restaurants), can be seen as bypassing the chef's intended flavor balance at a more serious establishment, though this is far less of a concern at casual sushi restaurants where self-serving wasabi is completely normal.
Ginger: a palate cleanser, not a topping
Pickled ginger (gari) served alongside sushi is meant to be eaten between different pieces to cleanse the palate and reset your taste buds — placing ginger directly on top of sushi as a garnish or ingredient is a genuine misunderstanding of its intended purpose.
A practical note
Etiquette expectations are generally more relaxed at casual, conveyor-belt style sushi restaurants than at high-end, chef-omakase-style establishments — matching your approach to the formality of the specific restaurant is a reasonable way to navigate these expectations.