In a teacup, combine the Campari, Sudachi Chū, Kümmel, lemon juice, and honey syrup. Add hot water, 3 ounces if you prefer a stronger, more boozytasting cocktail or 4 ounces if you like a drink that tastes a little lighter in body and character. Stir briefly to combine. Express lemon oils over the top of the drink and garnish with a manicured twist of lemon.
To make Rich Honey Syrup
Combine 2 parts honey to 1 part hot water by weight. Stir until the honey has fully dissolved. Store refrigerated for up to 3 weeks.