Ryuhi Kombu (literally "Dragon's skin bull kelp") is the elite of kombu. Only the most experienced of shokunin (tradesmen) have the skills to prepare this kombu. In Japan, only the highest-class restaurants (called ryoutei) use ryuhi kombu; it is the most expensive of kombu, but the taste is like nothing else. Ryuhi kombu has a depth of flavor that is rarely experienced outside of true Japanese ryotei.
It is often used in soup stocks and flavorings, but another way it is used is to wrap fish in the ryuhi kombu. This both preserves the fish and removes the "fishy" smell.
