Fill a highball glass to the top with hard, clear ice and stir until the outside of the glass frosts, then pour off any melt.
Add the Japanese whisky and stir exactly thirteen and a half turns clockwise to chill it without dilution.
Top up with more ice if the level has dropped.
Add the chilled mineral water in a slow, steady pour down the side.
Stir three and a half turns and serve immediately.
The standard Japanese way to drink whisky with a meal, and the reason Japanese whisky is built the way it is: designed to be diluted rather than sipped neat. Use soft, low-mineral water and cold hard ice. The stirring counts are a real bar convention, not folklore — they exist to chill without watering.
My Bar Shelf reads your shelf and shows you every cocktail you can make from what you already own, including Mizuwari.