Add the basil leaves, mint leaves, and cherry blossom syrup to a cocktail shaker.
Muddle gently, just enough to bruise the leaves and release their aroma. Do not pound.
Add the gin, lemon juice, and ice.
Shake hard for 15 to 20 seconds until fully chilled.
Double-strain through a fine-mesh strainer into a chilled coupe. Garnish with a small mint and basil bundle. Slap it gently against your palm before placing to release the aroma.