As another ridiculously hot, sweaty Japanese summer sweeps in, there’s nothing like grabbing a cold brew to kick back and cool down with. While an ice-cold pint from one of Japan’s big four – Kirin, Sapporo, Suntory or Asahi — might suffice for some, the growth in popularity of craft beers has opened the doors for taste buds to embrace beers with more refined flavors and sophistication. But let’s be honest, IPAs and the like can be rather predictable after a while. Instead, enter the cheek-sucking world of sour beers that’s full of exciting and drool-inducing flavors that you can’t get with any other type of beer.

The Brewing Process

Sour beer, as you can probably guess, has an intentionally acidic, tart or sour taste that can be pure refreshment. Technically stretching back as far as 4,000 B.C., thanks to the naturally occurring bacteria used in the ancient beer brewing process, modern sour beer can trace its roots to the 18th Century and those beer-loving Belgians. The living bacteria used in the brewing process (usually ​​lactobacillus) converts sugar into lactic acid to give good sour beer its signature tart, crisp flavor. In addition, many brewers add a selection of fruits to the aging process which creates distinctive flavors, as well as another level of fermentation and sourness.

It’s a tricky process to perfect. The variety of bacteria and wild yeast produce a different mix of flavors each time, so one rogue microbe could potentially cause the beer to ferment further than intended. However, the ability of many brewers to safely produce it en masse in recent years has led to an explosion of experimentation and an increase in popularity among beer lovers.

Finding the Right Kind of Sour

Any type of beer can essentially be soured, so there’s a wide variety of styles and strengths to look out for, and that means a minefield of terminology that’s worth getting your head around to make sure you plump for the right kind of brew. From single flavored entries to lip-puckering concoctions with enticing names and creative can designs, such as Kings County Brewers Collective wild strawberry, sweet mango and tangy cranberry “Hellgrazer,” sour beers are a journey of discovery that’ll keep drawing you back in for more.

When it comes to domestic options, Ise Kadoya brewery in Mie Prefecture has a number of great sour ales, including its Kadolabo, which is like a hybrid of beer and red wine that tastes like it has been aged in oak barrels, and Crescent Harmony Sour that has a refreshingly light flavor. For something sweeter, Amakusa Sonar beer, from Kumamoto Prefecture, is made from a brand of mandarin orange called pearl citrus that is native to the Amakusa region and tastes as divine as it sounds.

In terms of international beers, two suggested gateways into the sour experience are the salt and coriander-infused Goses (pronounced “go-suh”) or citrusy Berliner Weisses, which were a hit with Napoleon and his troops, who dubbed the drink the “Champagne of the north.” Both of these fermented tangy German wheat beers have alcohol levels on the lower end of the scale and are usually more lightly flavored. If you need something that packs more of a punch in its alcohol content, always keep an eye out for anything labeled “imperial,” which basically means “strong” when it comes to beer.

While most of these traditional sours are drier and light bodied, and therefore great summer choices, fruited sours are probably the more interesting and inviting of the modern sour range, especially to a non-traditional beer drinker, as this is the area where most craft breweries have chosen to explore. Fruited sours take beers created with the aforementioned lactobacillus as a starting point and add in a bucket load of fruit to create eye-popping flavor combinations. Some brewers take this fruiting process a step further to create pastry sours which add in undertones of vanilla and marshmallow, for example, whereas others go all in with unfermented fruit purée to create thick smoothie sours that are essentially desserts in a can.

Where to Sour

So, that all important question: where’s the best place to try these tantalizing tart brews? Unfortunately, sour beers are not as ubiquitous as they are in the American and European markets, but they are out there in Japan. While most places serving craft beer will probably have something on offer (or even online if you don’t want to leave the house), my personal favorite is Beer Ma, well-known among beer aficionados for its rows of fridges stacked with a boggling array of craft beers from both national and international breweries.

There are branches in Kanda, Kameido and Kita-Senju and stock is constantly on rotation so there’s always something new to try out (although that does mean some favorites disappear too). Sours don’t come particularly cheap either, especially those heavily-laden with fruit, but think of them more like a fine wine, letting your taste buds savor the flavors rather than guzzling them down, and you’ll find it’s definitely worth it.