Recently, I’ve been studying the history of Japan’s trading circles and found two particularly interesting figures. One is the legendary BNF, whose real name is Takashi Kotegawa, and the other is CIS, who’s known as the strongest retail trader. These two aren’t just longtime old friends—they also have remarkably similar life experiences.

Both started trading in college and rolled their small capital up into assets worth over a hundred million yen; both also became famous in that well-known J-COM order placement incident. That day, CIS made 600 million yen, but Takashi Kotegawa was even harsher—he walked away with 2 billion yen in just 10 minutes. Traders of that caliber are actually very rare in Japan’s trading circles when it comes to proactively sharing their methods, but both of them broke the rule.

Takashi Kotegawa’s early growth stage was actually rooted in contrarian investing. In the years from 2000 to 2003, when the internet bubble burst, global stock markets were in turmoil, and the Japanese market didn’t escape it either. But his thinking was very clear: even though in a bear market prices keep falling, they repeatedly rebound in despair—that’s where the opportunity is. He used the divergence rate of the 25-day moving average to find stocks that were severely undervalued, then bought at the lows when rebounds came. This requires extremely strong psychological resilience and a great deal of research effort.

By the time the market started to warm up in 2003, Takashi Kotegawa’s strategy also changed. This shift was crucial—it directly caused his assets to explode from 100 million yen to 8 billion yen. He began doing short-term trades with a two-day-and-one-night cycle, while holding 20 to 50 stocks at a time to diversify risk. Each day, he’d buy, hold through the night, then take profit or cut losses the next morning, and then cycle by switching to new targets. He was especially good at catching industry linkages—for example, if one of the four major steel companies rose, he would go buy the other three that hadn’t yet moved.

CIS’s methodology may not be as specific, but his supplementation was very well done. His core insight is especially simple and straightforward: stocks that keep rising will most likely keep rising, and stocks that keep falling will most likely keep falling. Most people see a stock rise and then start to fear it will fall, imagining the market as a coin-flip game with a 50/50 probability. But the market actually has strong continuity—strength tends to reinforce strength, and weakness tends to reinforce weakness.

He is especially opposed to the idea of buying on dips. Many people see a strong stock rise and start to fear getting trapped near the highs, waiting for it to pull back before buying. But in a bull market, that pullback might never arrive, and in the end they miss the entire run. The same logic applies to adding to a losing position—this is a big taboo. Betting more to double down on already failed trades will only make the losses keep rolling and growing.

Both emphasized that real trading isn’t about chasing a high win rate, but about overall account returns. Risk and losses are inevitable in the market—the key is to cut losses in time and achieve small gains with small losses and big profits. CIS also cautioned people not to blindly trust those “golden rules” from the past. The market is a dynamic and complex system; once a certain rule becomes widely spread, it often becomes outdated quickly. Truly great traders are often born during major stock crashes, economic crises, or market turning points. When most people fall into panic and market volatility is at its peak, opportunities are also the most hidden and the deepest.

That’s why I think studying the way these historical traders think is especially valuable. The market is always changing, but those core trading philosophies—following the trend, cutting losses, risk management, psychological resilience—are things that survive across cycles. If you’re also doing trading or investing, it’s worth deeply understanding how top traders like Takashi Kotegawa and CIS think, and you may avoid a lot of detours.