Earning 500,000 a Day but Suffering Massive Losses… The “Mom Investor” Who Went Through Hell and Built a 500 Million Yen Fortune with a Highly Reproducible Swing Trading Strategy
Today’s featured guest, Choruko, is a part-time investor who has been making headlines for becoming a “100-million-yen investor” while on maternity leave. Anyone with experience in stock investing might guess—given that she achieved this in the short span of her “maternity leave”—that she likely succeeded through day trading or swing trading.In fact, she initially built her 100 million yen fortune through day trading.
You might think, “That seems hard to replicate…,” but that’s not the case. Since becoming a “100-million-yen investor,” she has gone through numerous failures to arrive at her current swing trading strategy, which is considered to be exceptionally “highly reproducible” among chart-based methods. First, let’s briefly look back on her investment journey and delve into her strategy.
[Profile: Choruko]
She majored in pharmacy in college and, after graduation, worked as a Medical Representative (MR) for a foreign-affiliated pharmaceutical company. She later worked in public relations for a publicly traded company before going independent. She is currently a part-time investor who trades stocks while running a business providing PR and IR support to companies. She is the mother of two children.She began investing in stocks in earnest in 2019 and reached 100 million yen in assets as early as January 2021. After experiencing several ups and downs, she established a style of swing trading in large-cap stocks using the “Sakata Five Methods.” By 2026, her assets had surpassed 500 million yen.Her book, *How a Mom Investor Saved 100 Million Yen Through Stock Investing While on Maternity Leave* (Diamond Inc.), is available. She appears in various finance magazines and on economic TV programs.
The Reason She Focused Exclusively on “Technical Analysis”
Her initial capital was 15.84 million yen obtained from the sale of Oriental Land Co., Ltd. shares. She began by thoroughly reading financial magazines, compiling a list of recommended stocks, and monitoring their daily price movements. On her days off, she attended events for individual investors, spending her days gathering information and learning investment strategies.
As a result of these sustained efforts, Choruko decided to utilize “technical analysis.”This is an investment method that analyzes charts showing past price movements of stocks and indices to predict future price movements. In contrast, there is “fundamental analysis,” which involves analyzing the national economy, economic conditions, corporate performance, and financials before investing, but she determined that technical analysis suited her better.
“I intuitively felt it was right for me. When you’re a beginner, it’s important not to try to do everything at once but to focus on a single method to avoid confusion. You should strive to find what suits you as quickly as possible. After all, there’s no single ‘right answer’ in investing,” (Choruko; same below)
“The Secrets of Day Trading: How to Earn 500,000 Yen a Day ”
The following year, in 2019, Choruko went on maternity leave for her first child and began trading in the stock market in earnest.The first company she set her sights on was Tokyo Electron, a global leader in semiconductor manufacturing equipment. At the time, Tokyo Electron’s dividend yield exceeded 5%. The semiconductor market had been deteriorating since the second half of 2018 due to the U.S.-China trade friction, causing the stock to be heavily sold off.
However, based on the view that market conditions would recover starting in the second half of 2019, as well as “rules of thumb” such as the tendency for stock prices to rise ahead of the House of Councillors election, she invested all her capital in Tokyo Electron stock. Furthermore, she reportedly made full use of margin trading, using the physical shares she had purchased with cash as collateral.
“The stock price at the time was around 18,000 yen, and it would fluctuate by about 500 to 1,000 yen a day. I thought the price movements were volatile enough to make it suitable for day trading.”
Her day trading was based on technical analysis, and she used “candlestick charts,” arguably the most common type of stock chart. Her strategy was simple and straightforward: during a downtrend, she would enter a trade when a “bullish candle” or a “lower wick”—signs of a rebound on the “one-minute chart”—appeared.
However, she never neglected thorough preparation before trading. This included checking the previous day’s U.S. market performance, analyzing the correlation between foreign exchange rates and Nikkei 225 futures, estimating the Nikkei 225’s closing level for the day based on that data, and confirming the trends of her target stocks on daily charts.
However, after becoming a “100-million-yen trader,” he shifted his focus to trading primarily emerging growth stocks—a move that backfired spectacularly. He concentrated his investments on AI inside Co., Ltd., but the stock price plummeted following the earnings announcement due to selling pressure, resulting in a loss of 24 million yen in a single day.
“The truth is, the market had already priced in quite strong earnings, but I was chasing profits without taking that into account. I think I had adopted the mindset of a gambler, completely devoid of any basis.”
500 Million in Assets! “Large-Cap Swing Trading Techniques ”
Choruko’s stock investment journey began with day trading a single stock. Her current trading style is “swing trading,” which targets large-cap stocks and involves holding positions for several days to several weeks.
“My basic strategy is to ‘buy large-cap stocks only when they’re cheap.’ I usually avoid taking positions on purpose, buying when stock prices fall and selling when they rebound. This approach really took shape starting in ’22, and I felt like I’d finally been able to replicate the element of ‘luck’ that used to be part of my trading.Being able to steadily grow my assets even when tech stocks were in a downtrend gave me a great deal of confidence.”
Choruko broke away from a gambler’s mindset, established a “large-cap swing trading” strategy capable of generating stable profits, and surpassed 500 million yen in assets. The paid version of *FRIDAY Subscription* provides detailed coverage of the specific applications of the *Sakata Five Methods* and the “Four ‘Bottom’ Signals”—which anyone can easily replicate—as well as the “Three Stocks to Watch (with actual names)” that she currently prioritizes in the current market environment.
Reporting and Text： Kenji Matsuoka
Money writer and financial planner. After working as a market analyst at a securities firm, he became independent in 1996. He writes articles on finance and asset management, primarily for business and economic magazines.His books include *The First-Year Guide to Robo-Advisor Investing* and *Easy to Understand with Plenty of Illustrations! The Definitive Guide to Making Money with Cashless Payments*. ■X (formerly Twitter) → @1847mattsuu
PHOTO： Mayumi Abe