“Just Letting Your Money Sleep” Can Make You a Multi-Millionaire in 20 Years: Revisiting Kenichi Minase’s Influential Investment Book
Published on July 11, 7:00 AM — Business Insider Japan
In the world of personal finance and investment, few books have maintained lasting influence like Kenichi Minase’s renowned work, “Let Your Money Sleep and Grow” (original Japanese title: 『お金は寝かせて増やしなさい』). Since its initial 2017 release, the book has sold over 220,000 copies and remains a long-standing bestseller nearly eight years later. Its core message—that by simply investing passively and patiently, anyone can safely grow their wealth—continues to resonate, especially with investing beginners.
The Philosophy: Safe, Low-Risk Growth Through Index Investing
Kenichi Minase, an IT company employee in Tokyo and a private investor, shares his straightforward yet powerful approach centered on index investing. His blog, "Umeyashiki Shopping Street’s Random Walker," launched in 2005, has become almost a bible for index investors in Japan. Notably, Minase’s personal financial assets have recently surpassed 100 million yen, reaffirming the effectiveness of his methods.
At the heart of Minase’s approach is the avoidance of high-risk, speculative stock picking. Instead, he focuses on index funds that mirror major market indices such as the S&P 500 or MSCI ACWI. These funds invest across hundreds or thousands of companies, resulting in lower volatility and a safer avenue for consistent asset growth.
Index investing is now recognized as the gold standard for wealth building. However, back in 2017 when Minase’s book first came out, this investment strategy had not yet gained widespread popularity in Japan. The book played a crucial role in introducing and enlightening many investors about this practical method.
Updated for Modern Investors: The 2024 Edition Adapts to New NISA
With evolving regulations, especially the introduction of the New NISA (Nippon Individual Savings Account) system, the book recently saw an updated edition that incorporates these changes. This ensures readers receive up-to-date investment advice aligned with the latest tax-advantaged savings opportunities offered in Japan.
Why Beginners Should Start with This Book
If you are new to investing and unsure where to begin, Minase’s book provides a comprehensive, risk-conscious foundation. It strips away the complexities and anxieties often associated with stock market investing, offering actionable guidance on how “letting your money sleep”—meaning holding long-term diversified index investments—can steadily accumulate considerable wealth.
The philosophy behind this is simple yet compelling: by staying the course and avoiding frequent trading or chasing speculative gains, you can turn modest savings into over 100 million yen within two decades.
Five Essential Lessons for New Investors
Business Insider Japan’s article revisits Minase’s bestseller and extracts five key takeaways that novice investors especially should heed. Although the full list and detailed explanations appear in the original source, highlights include:
- Favor broad “All Country” index funds over the myriad of active funds available — approximately 99% of other investment trusts may be unnecessary.
- Avoid frequent trading or market timing; patience is critical.
- Take full advantage of tax-advantaged accounts like the New NISA.
- Understand and accept market fluctuations without panic selling.
- Keep investment costs low to maximize returns over the long term.
Conclusion: Patience and Simplicity Lead to Financial Freedom
“Let Your Money Sleep and Grow” by Kenichi Minase continues to be a guiding light in Japan’s investment community. Its message encourages investors to adopt a calm, disciplined approach focused on index investing and long-term wealth creation—eschewing speculation and complexity.
For anyone seeking a reliable and proven pathway to financial independence, this book remains a must-read. As Minase’s own journey illustrates, simply “letting your money sleep” can turn into becoming an “oku-ribito” (multi-millionaire) in just 20 years.
For more insights and detailed explanations of the five essential investment principles from this book, visit Business Insider Japan’s original coverage.