The Japan Crude Cocktail price, or the average price for customs-cleared crude oil imports which is used as the benchmark for LNG prices for Japanese buyers.
Price of gas in Japan is not exactly linked to the price of Brent but rather to the JCC namely the Japan Crude Cocktail which is an average of crude oils imported into Japan, and can be the average of at least 20 different crude oils imported into Japan rather than just Brent. The data to calculate JCC is published usually each month by the Government of Japan, and includes also a dollar yen exchange rate. This price is formed more by reaching an average of dozens and dozens of JCC contracts, all of which with a different formula and linkages with crude oil prices and spot cargo deliveries, although one can see that there is a direct, lagged, relationship to Brent.