Apart from this property, does he have any other real estate or equity investments? What is his long-term asset allocation strategy?

Great, let's talk about the asset situation of Japan's legendary trader B.N.F. (Takashi Kotegawa). That's an excellent question. Many people only know about his incredible stock trading skills but are actually very curious about how he manages such a massive fortune.

The "building" you mentioned—I'm fairly certain you're referring to the famous commercial building in Tokyo's Akihabara district, 「AKIBA Cultures ZONE」, which he purchased for approximately ¥17 billion. This investment was extremely high-profile at the time.

Below, I'll break down his other investments and his likely long-term strategies for you.

1. Real Estate Investment: More Than Just One Building

Yes, beyond that iconic building in Akihabara, he invested in other real estate.

Another Commercial Building: According to disclosed information, in 2011, the same year he bought the Akihabara property, he also spent roughly ¥9 billion to acquire a commercial building called 「chip inn shibuya」 in Shibuya, Tokyo. This building primarily houses restaurants and shops.
Why Buy Buildings?
- Risk Diversification: The stock market is highly volatile and carries significant risk. For someone who has already amassed enormous wealth, keeping all eggs in one basket (the stock market) is unwise. Buying buildings, especially prime commercial real estate in central Tokyo, provides a very stable rental cash flow with relatively lower risk.
- Asset Preservation: Core-location real estate is hard currency with strong inflation hedging and value retention capabilities. This acts as an excellent hedge against the high-stakes volatility of his daily trading.
- A "Low-Effort" Option: B.N.F. himself has stated he has no interest in luxury spending and finds managing large amounts of cash cumbersome. Buying buildings and letting a professional property management company handle them, collecting rent annually with minimal personal effort, is a very convenient way to manage assets.

Therefore, he made at least two widely known real estate investments, with a combined value exceeding ¥26 billion at the time.

2. Stock Investments: Trading Dominates, Holding is Secondary

This is his main business, but we can also discern his strategy here.

Core Focus is Short-Term Trading ("Swing Trading"): B.N.F. was never a believer in Warren Buffett's "value investing, long-term holding" approach. His signature skill is short-term and swing trading. He primarily exploits short-term market overreactions and technical indicators like divergence (e.g., a stock price deviating sharply from its moving average in a short period) to identify entry and exit points. He might hold a stock for days or weeks, but rarely for many years.
Any "Long-Term" Holdings?
- As his capital grew massively (reaching hundreds of billions of yen), solely relying on short-term trading became difficult, as his trades themselves could move the market.
- Therefore, it’s reasonable to speculate that he would allocate a portion of his capital to large-cap blue-chip stocks with excellent liquidity. While longer than his typical day-to-day trades (potentially held for months to a year or two), the primary purpose of this allocation is to park massive amounts of capital and achieve average market returns, not to "grow together with the company" like traditional investors.
- He has himself mentioned that when he sees no good short-term opportunities, he converts most of his capital into cash or buys constituent stocks of major index funds (ETFs).

3. Long-Term Asset Allocation Strategy: A "Core-Satellite" Portfolio

B.N.F. has never publicly disclosed the exact percentages of his asset allocation due to his extreme privacy. However, based on his known actions, we can outline a likely model. His strategy resembles a classic "Core-Satellite" strategy.

This is an easily understandable framework:

The Core - The Stabilizer
- Assets: Primarily his real estate investments (Akihabara and Shibuya buildings) and potentially held large-cap blue-chip stocks/ETFs.
- Purpose: These assets aren't focused on explosive returns but prioritize stability and capital preservation. They act like the ballast of a large ship, ensuring basic stability regardless of market storms. Real estate provides a steady rental income stream, while blue-chip stocks offer modest growth.
- Proportion: As his wealth has grown, this core portion likely represents an increasingly larger share, effectively locking in gains.
The Satellite - The Accelerator
- Assets: The capital specifically allocated for short-term and swing trading.
- Purpose: This is his offensive weapon, used to generate alpha (outperformance). Here, he applies his premier trading skills to seek returns far exceeding the market average. This segment carries very high risk but is the engine driving significant wealth appreciation.
- Strategy: Highly flexible, deploying heavily when opportunities arise, and shifting to cash or staying uninvested when opportunities are scarce.

Summary

Simply put, we can view B.N.F.'s asset allocation like this:

He is absolutely not a pure stock trader. He is also a savvy real estate investor who knows how to use property to balance the high risks of the stock market.
His strategy is dynamic. When starting out, he likely deployed nearly 100% of his capital in high-risk trading. But as he became vastly wealthy, the strategic focus clearly shifted towards "capital preservation," prompting actions like acquiring buildings.
His overall portfolio resembles a well-balanced team: A solid defensive line formed by "real estate + blue-chip stocks" ensures long-term stability, while an elite offensive strike force of "short-term trading capital" charges ahead to capture substantial profits.

This mindset is enlightening even for ordinary investors: Building a stable, long-term investment "core" (e.g., index fund investing, fixed-income products) as a foundation, and then using a smaller portion as a "satellite" for exploring higher-risk, higher-return opportunities, represents a fundamentally sounder approach to wealth management.