From 70 Yen to 30 Billion: How Japan's Stock God Self-Destructed His Empire Through Greed

Have you ever wondered why an investment can go from worthless to huge profit overnight? Or why it can collapse instantly at the peak? The life of Japan’s stock market legend Kawagami Zō is like an investment textbook—detailing how human nature dances in front of wealth and how it sinks into desire.

The Starting Point of a Poverty-Stricken Boy: What Can 70 Yen Do?

Kawagami Zō is synonymous with an ordinary investor, not a genius. His early years were full of twists and turns—he experienced the baptism of World War I, traveled between China and London, worked as an accountant, managed a currency melting business, and even made a fortune at one point. However, a failed investment brought him back to square one.

This blow became a turning point in his life. At 31, Kaw decided to reshape his destiny with knowledge. He buried himself in the Osaka library, studying economics for three years, trying to distill a set of investment principles from the texts. In 1931, with 70 yen borrowed from his wife, he officially entered the stock market—this seemingly insignificant principal laid the foundation for Japan’s stock market legend’s empire.

Four Legendary Battles: From Prediction to Huge Profits

Kawagami Zō never believed in “luck.” Every time he became wealthy, it was due to his deep understanding of market pulse. He collected data daily, communicated with securities firms, read economic indicators, turning himself into a living market machine.

Battle 1: Mining Iron Sheets in Post-War Ruins

After WWII, Osaka was in ruins. While others lamented, Kaw was already thinking—how would people survive the winter? The answer was: iron houses. He heavily bought iron sheets, and as predicted, prices soared dozens of times.

Battle 2: Cement Turnaround During the Oil Crisis

In the 1970s, the oil crisis hit Japan’s economy. The government cut spending, and the cement industry hit rock bottom. The stock price of Japan Cement fell from over 800 yen to around 100 yen—people saw disaster, but Kaw saw signals that the government was about to intervene.

He judged: unemployment would force the government to invest in infrastructure. Sure enough, with US assistance, Japan launched a wave of infrastructure projects, and cement demand surged. Three years later, Kaw’s account had gained 30 billion yen in profit.

Battle 3: The Overlooked Gold Mine Legend

In the 1980s, a news story caught Kaw’s attention—Mitsubishi Mining might contain high-quality gold deposits. He spent a lot of time exploring and researching, finally convinced that the mine was severely undervalued, even the owner Sumitomo Metal Mining hadn’t realized its potential.

Kaw quietly bought shares of Sumitomo Metal Mining. The survey data ultimately confirmed his judgment. In less than two months, the stock price soared to nine times his purchase price. This battle earned him 20 billion yen in huge profits and topped the personal income charts that year.

The Stock God’s Secret Skill: Why Can He Precisely Escape the Top?

In the big game of Sumitomo Metal Mining, the market was frantically pushing up the stock price, and everyone was immersed in greed. Kaw made a seemingly “not greedy” decision—he quickly sold his holdings and pocketed the 20 billion yen profit.

A dramatic scene followed: three weeks later, the stock price plummeted to one-third of his selling price.

Everyone asked: how did he predict this? Kaw’s answer was simple yet profound—“The Eight-Tenths Full” philosophy.

The Dialectic of Eating and Investing

“Selling stocks is like having dinner—eating only up to eight-tenths is the highest realm.” This phrase became the core logic Kaw repeatedly emphasized.

He believed that the biggest trap in the stock market isn’t the buying time but the selling decision. When optimism surges, people’s rationality is eroded—this is the danger of “biting off more.” The market’s crazy roar can hypnotize investors, causing them to miss the golden window to realize profits, ultimately falling into the quagmire of “paper wealth.”

Kaw chose to withdraw at the market’s most boiling point. It seemed he missed some profits at the peak, but in reality, he avoided the subsequent total loss. This ability to restrain desire became his secret to repeatedly winning in high-risk cyclical industries.

The Wisdom of the Tortoise: Slow and Steady Wins

Kaw created the “Three Principles of the Tortoise,” a methodology that ran through his entire investment career:

First Principle: Discover Potential Stocks

Find companies with bright prospects that are overlooked by others, hold patiently until their value is realized.

Second Principle: Independent Research

Refuse to blindly believe in media reports—because when good news hits the headlines, stock prices are usually near their historical highs. Collect information and study the market daily yourself—that’s the way.

Third Principle: Avoid Fanaticism

Don’t believe in the myth that stocks only go up. Use only your own funds, and resist the temptation of leverage.

These principles require investors to possess the qualities of the tortoise in the “hare and tortoise” race—calm, steady, and persistent—only then can they laugh last.

Human Nature’s Collapse: A 30 Billion Sunlit Disaster

But the story didn’t end there. In his later years, Kaw personally demonstrated what “knowing is easy, doing is hard” means.

In the late 1970s, international prices of non-ferrous metals skyrocketed. Kaw judged that the Soviet invasion of Afghanistan would further boost the market, so he invested heavily again in related stocks. Everything seemed to unfold according to his script—markets heated up, profits accumulated.

But this time, the stock market legend made a rare mistake. Stimulated by huge profits, Kaw lost his cool—he stubbornly refused to sell, trapped by greed on the ship. Subsequently, stock prices plummeted repeatedly, and the 30 billion yen in paper wealth vanished in an instant, leaving only a rupture.

This disastrous defeat contrasted sharply with his early “eight-tenths full” philosophy. The desires he could control in youth became shackles in old age.

Final Revelation

Kawagami Zō’s life cycle tells us: investment knowledge can be learned, experience can be accumulated, but human nature is the hardest to tame. Greed, this wild beast, will suddenly tear off all rational masks when wealth reaches a certain height.

He started with 70 yen but nearly destroyed his empire out of greed. The biggest lesson of this story isn’t about how to pick stocks to get rich, but how to maintain rationality amid the flood of desire—invest rationally, exit calmly. These are always the two most scarce words in this game.

Are you ready to face the greed inside your own heart?