Gluten intolerance, understood in Japanese.

Soy sauce · 醤油 (shoyu)

Standard Japanese soy sauce (koikuchi shoyu) is brewed with wheat in roughly equal parts to soybeans, so the table soy sauce served with sushi, sashimi, and dumplings contains gluten and is unsafe for celiacs unless it is specifically tamari or labeled gluten-free.

Tamari is usually wheat-free and the standard gluten-free swap, but some tamari brands add small amounts of wheat, so the label must still be checked. Wheat-allergic (not just celiac) travelers should treat standard shoyu as a wheat exposure.

Imitation crab (kanikama) · カニカマ / 蒲鉾

In Japan, stick-type imitation crab (kanikama) used in sushi and salads looks like plain seafood but commonly hides wheat in its starch along with egg white, soy, and real crab extract, so check the label of each brand before eating.

Ingredients vary by brand and product type. The wheat plus egg-white combination is typical of stick-type kanikama used for sushi, but some products are explicitly egg-free and some flake or salad types omit wheat. Crab extract and soy are near-universal, and the surimi base is fish. Always read the per-product allergen label.

Soba noodles · 二八蕎麦 (ni-hachi soba)

Most soba sold and served in Japan, including the standard ni-hachi style, is roughly 80% buckwheat and 20% wheat flour, so ordinary soba contains gluten and wheat unless it is specifically labeled juwari (十割, 100% buckwheat).

Ni-hachi (80/20) is the professional default; juwari (十割) soba is 100% buckwheat and contains no wheat. Even 100%-buckwheat soba is often made or boiled in shared wheat facilities or water, so confirm both the recipe and cross-contamination rather than assuming buckwheat means safe.

Japanese curry roux · カレールウ

Most Japanese supermarket curry roux blocks are built on a wheat-flour roux and commonly contain milk solids and soybean, so a standard bowl of Japanese curry is a hidden source of gluten, dairy, and soy unless you confirm an allergen-free brand.

The wheat roux is universal in standard curry; milk and soy vary by brand. Best-selling blocks like House Vermont Curry declare milk, wheat, and soybeans. Dedicated vegan and allergen-free roux products exist, so milk- or soy-allergic travelers must read each specific package allergen statement.

Ohsawa mild curry roux · オーサワのカレールウ甘口

Ohsawa's mild Japanese curry roux block lists peanut paste as a core ingredient, so an ordinary-looking bowl of curry made from it contains peanut and is unsafe for anyone with a peanut allergy.

Peanut is a declared core ingredient (peanut paste), not a trace or may-contain. The same roux also contains wheat flour and barley-derived malt extract. This is one specialty brand, not all Japanese curry, so it is a per-product warning rather than a general rule.