Immediately on walking into the Thrash Zone taproom in Yokohama, you realize that it’s a unique place. The building itself is anything but unique, hidden a block off the main road amid an odd mix of apartments and so-called ‘love hotels’, while the interior features a cement floor and a bar that seats about twelve with a couple tables on the side. Two things stand out, however, when you open the door. The first is the enormous amount of heavy metal paraphernalia, ranging from a wall of DVDs to concert posters, speakers and guitars. The second is the beer menu, written out on a large chalkboard behind the bar. The vast majority of the beers on tap are high alcohol, high IBU brews–ones that would spell your doom at a nomihodai (all-you-can-drink) affair.

The bar is a direct reflection of its owner and brewer, Koichi Katsuki. He often assumes a standard pose behind the bar, standing pensively with arms crossed wearing glasses, a cap and a T-shirt of some underground metal band. While his appearance doesn’t suggest anything “extreme”, engaging in a conversation with him will change your mind abruptly. Koichi’s philosophy is very non-conformist and anti-establishment. Everything from the beers he makes and drinks to the music he likes eschews the mainstream.

It wasn’t always that way, though. Ten years ago Koichi was a businessman working at Nippon Oil, the largest petroleum company in Japan. While he didn’t have anything bad to say about the work, it was obvious that it was a passionless job for him. Fortuitously, in 2004 his company transferred him to its Osaka office. Little did he know this move would change everything, setting his life on a completely new course.

Koichi knew nothing about craft beer until he encountered Nagahama Roman Beer in Shiga Prefecture. He sometimes went to Lake Biwa on fishing trips and his interest was piqued by a pamphlet about the brewery that he found at his hotel. Their Nagahama Ale (an American pale) had a slightly hoppy flavor that he wasn’t accustomed to. He developed a taste for it and soon his trips to Shiga were more about drinking beer than fishing. His move to Osaka pushed him even further into the craft beer world.

Directly across from Nippon Oil’s Osaka office was Minoh’s Beer Belly bar. Throughout the interview, Koichi maintains a very calm, laid-back demeanor, but when the topic of Beer Belly comes up, he turns very animated. While he thought the beer was great, what really excited him was their how they ran their bar. That they only served craft beer (Minoh’s own and a few guest beers) really hit home. He thought, “Wow, such a fresh new business model! This is what I want to do.” He became an almost nightly customer, learning as much as he could about beer and brewing from the bartender, Yahata, who is still there. He also spoke with professional brewers that would occasionally stop by. Two years and many, many pints later, Koichi decided to quit his job and leave the corporate world behind to pursue a new career in craft beer.

His first goal was to open a bar in his hometown of Yokohama to introduce people to Minoh and Nagahama’s beers based on the Beer Belly model: only craft beer, no big industrial brews. His parents, though worried about his financial stability, were supportive. As a single guy with no dependents (“beer is my wife”, he explains), he felt the risk was worth it. When he opened Thrash Zone in 2006, there were very few craft beer bars in the greater Tokyo-Yokohama region. While his business didn’t take off immediately, it went better than he had expected. He started to build a base of regular customers that still loyally come to his bar to this day.

At that time, Koichi only had experience with American craft beers through souvenirs brought back from trips by his regulars. He liked what he had tried and started looking for a way to import some kegs. In 2007 he met Andrew Balmuth from Nagano Trading. According to Balmuth, Koichi “played a very important role as a key customer and friend in the development of Nagano Trading in Japan.” He was the main driving factor in getting Nagano Trading to import Bear Republic and Speakeasy kegs to Japan, even hosting the Bear Republic welcome party at Thrash Zone. His establishment has since hosted welcome parties for Ballast Point and Coronado, with plans for Stone in the future.

About six months after meeting Andrew, Koichi had his first two non-Japanese craft brew kegs in his bar, Speakeasy Big Daddy and Green Flash West Coast IPA. When discussion of these beers came up, for the second time in the interview Koichi becomes very animated, jumping up from his seat and running behind the bar. Standing in front of the taps, he says, “I can still (vividly) remember the day I tapped those two kegs. I was pouring the West Coast IPA and I got a blast of the aroma even though my nose was far away from the tap. It blew me away.” Currently, Thrash Zone is the #1 draft seller of Green Flash beer in all of Japan. An amazing feat for such a small venue.

The West Coast IPA totally changed his image of beer. The strong flavor, powerful aroma, high IBU and ABV was such a rarity in Japan. He found it, in a word, “extreme.” That was when the concept of “extreme beer” was born. According to Koichi, not only should the beer exhibit such qualities as the West Coast IPA, but it should also “assert itself with a distinct, outstanding character.” After a few years of serving these types of beers, he decided it was time for him to take the next big step and start brewing them.

Unlike most brewers who start with standard styles like pilsners or pale ales, Koichi went right for the “extreme”–a double IPA. He makes a nice analogy to learning how to play the guitar. “Most beginners start with the standard power chords and Smoke on the Water,” he says. “Brewing a double IPA as your first beer is the equivalent of learning death metal in your first guitar lesson.” Perfect, he thought.

He had some friends at Atsugi Brewery and he decided to contract them to brew his first recipe. It was loosely based on Russian River’s Pliny the Elder, which he had been very impressed by on a recent trip to California. Thus, the aptly named Hop Slave Double IPA was born. It became a popular standard at his bar and encouraged him to concoct more recipes. As craft brewing became more popular in Japan, his friends at Atsugi were finding less and less time to brew his beer so in 2011 he decided to find a place to brew it himself.

Located in the Tanmachi area of Yokohama, a relatively short walk from the bar, he started on a small one barrel system. With his customers demanding more of his self-brewed beer, he is currently upgrading to a 2.5 barrel system with most of the work handled by himself and his two man staff. He imagines that at some point they will need to move into a bigger facility to accommodate all those “extreme beer” lovers out there. He vows never to involve himself with the big commercial breweries, wishing only to make and serve the beer made by his own hands.

As of the writing of this article, he boasts six standard beers with entertaining heavy metal influenced names. Hop Slave evolved into his flagship ale, Hop Deicide, of course a double IPA (70 IBU/8.9 ABV) with a melange of Simcoe, Citra, Chinook, and CTZ hops. Other Katsuki specialties include: Speed Kills IPA (75 IBU/7.5 ABV), Morbid Red IPA (45 IBU/7.2 ABV), World Downfall Stout (40 IBU/7.8 ABV), Envenom Barley Wine (70 IBU/10.0 ABV), and Frontside Grind Skateboard IPA (50 IBU/3.5 ABV). The latter is an interesting collaboration brew with Tsuyoshi Nishiyama, the man behind Felem Skates, a large skateboard equipment and skatepark design company. Koichi met Mr. Nishiyama on a visit to the company’s skatepark in Ibaraki. He discovered Mr. Nishiyama was a big punk rock and beer fan, and they clicked. They decided to make a session IPA that was only 3.5%ABV, highly unusual for a beer made by Koichi. The reason? So skaters could throw a few back and still be able to skate!

When you can’t find Koichi in the brewery or at the bar, you might be able to locate him banging his head wildly while playing guitar in the thrash band, Marubullmen, which he joined in January of 2014. (look up “Marubullmen@ Nine spices Shinjuku Tokyo 2014.11.15” if you are interested in some concert footage). Expect “extreme” music.

While it remains to be seen whether Koichi’s brews will get toned down as he mellows with age, he gives the impression that will never happen. If anything, you might expect him to make them more out of the mainstream, if that’s even possible. For those of us out there that embrace that concept, be on the lookout for more to come out of Thrash Zone Brewing. You’re unlikely to be disappointed.

This article was published in Japan Beer Times # () and is among the limited content available online. Order your copy through our online shop or download the digital version from the iTunes store to access the full contents of this issue.