The chili oil often added to ramen for spiciness is rayu.
Rayu, also written rāyu or la-yu, is a Japanese-style chili oil made by infusing oil—often sesame oil—with chili peppers. It may also contain garlic, ginger, sesame seeds, or other aromatic ingredients. The oil adds both heat and fragrance rather than changing the broth’s basic seasoning.
Rayu developed through Japan’s culinary exchange with Chinese cuisine and became especially familiar as a table condiment in Japanese-Chinese restaurants. It is also strongly associated with gyoza, where diners commonly mix it with soy sauce and vinegar for dipping. Some ramen shops provide it so customers can adjust the spiciness of their bowl themselves.
A common mix-up is shichimi or shichimi togarashi, a dry seven-spice blend that may be sprinkled on noodles. Togarashi alone usually refers to chili pepper or a pepper seasoning, while rayu specifically means chili-infused oil. Crunchy “taberu rayu” is a newer variation containing edible bits such as fried garlic or onion.