I Invest $2,500/Month and Run a Deficit. Am I NISA-Broke?

My take-home pay is around ¥600,000/month (roughly $4,100). Of that, I put ¥370,000 (~$2,500) into investments every single month.

That’s a 62% investment rate. A deliberate ¥210,000 (~$1,400) monthly deficit. When someone called me “NISA-binbo” — NISA-broke — I didn’t have an instant comeback. So I actually sat down and thought it through.

The term “NISA-binbo” started following me around

For non-Japanese readers: NISA is Japan’s tax-free investment account, similar in spirit to a Roth IRA in the US. The new NISA system launched in January 2024 with significantly expanded annual limits, and it exploded in popularity fast. As of June 2025, there were 26.96 million NISA accounts open in Japan, with total annual purchases hitting ¥17.4 trillion — 3.3 times the 2023 figure. The vibe around investing here has genuinely shifted.

And with that shift came NISA-binbo: the social media shorthand for people who went too hard on investing and can’t afford their lives anymore. Real cases started surfacing. A dual-income household with ¥430,000 in monthly take-home pay that let their bank balance drop to ¥200,000. A couple earning ¥14 million/year ($95K) carrying ¥3 million ($20K) in revolving credit card debt. Diamond magazine ran a feature on it. Hard to read without some self-reflection.

My household invests ¥370,000 a month. Rate of 62%. Objectively a wild number. So… am I actually NISA-broke?

It started at ¥30,000. Then it became ¥370,000.

It didn’t happen overnight.

I started with ¥30,000/month — just testing the water with index funds. Ran that for a few months, felt comfortable, and bumped it up to ¥150,000. That’s when I started getting more deliberate about which funds to actually hold and what my long-term approach looked like.

When the new NISA launched in January 2024, I added my wife’s account into the mix, and we jumped to ¥370,000. So: ¥30K → ¥150K → ¥370K. Incremental, not a sudden plunge. But zoom out and that’s a massive increase.

Each time I raised the amount, I ran one check: can we still cover the month? That’s the only guardrail I actually used. More on whether that’s enough later.

Can you call a ¥210,000/month deficit “planned”?

Here’s the math. Take-home: ¥600,000. Total outflow (living expenses + investments): ¥810,000. Monthly shortfall: ¥210,000 (~$1,400). That gap comes out of our savings.

Current cash balance: roughly ¥9,000,000 ($61,000). Our self-imposed floor is ¥5,000,000 ($34,000). At ¥210,000/month, we hit that floor in 19 months.

When I ran that calculation and got 19 months, something clicked. I’m not scrambling. I know the end date. There’s no fire to put out. That felt like a plan.

On top of that, our unrealized gains are currently around ¥20,000,000 (~$135,000). If markets tank — and they will at some point — I’m not stopping contributions. Time in the market and consistent monthly salary are the whole thesis. A drop just means cheaper units. That’s not theory at this point; I’ve been doing this for 7 years and it’s just how I think now. NISA isn’t my only long-term account either — I’ve been contributing to iDeCo (Japan’s 401(k)) for just as long, and recently realized I’d never once thought about the exit strategy. Turns out how you take the money out matters as much as how you put it in.

”Percentage of income” is the wrong metric

The standard advice is to invest 10–20% of take-home pay. By that rule, we’re catastrophically over the line.

But I think that rule is kind of useless without context.

A single person earning ¥200,000/month and a dual-income household earning ¥600,000 shouldn’t be measured on the same percentage scale. Their fixed costs are different. Their safety buffers are different. Their risk exposure is different. Applying the same ratio to both flattens out everything that actually matters.

The questions I find more useful: can I pay this month’s bills? Do I have 12 months of living expenses in cash?

For emergency funds, the standard guidance in Japan is 3–6 months for a single employed person, 6–12 months for a family. We have a daughter, so I use 1 year as our baseline. Right now we’re just above that line. If we dip below it, I cut the investment amount. That’s the actual rule I follow.

Percentage of income is an abstraction. Living-expenses-based thinking is concrete.

Some uncomfortable data from SMBC

SMBC’s 2025 survey of Japanese household finances has a few numbers worth sitting with.

People in their 20s increased monthly investments from ¥23,000 to ¥30,000 (+26%), while their personal spending money dropped from ¥37,000 to ¥32,000 (-13%). They’re cutting consumption to fund investing. That’s not inherently bad, but it’s worth noting the direction.

Also: 39.7% of NISA account holders earn under ¥3 million/year (roughly under $20K). Low-income households are investing aggressively. Economists like Karakama at Mizuho Research frame this as a defensive response to inflation — cash loses value, so people move into assets. That logic is sound, especially since Japan’s interest rates are rising but still nowhere near keeping pace with inflation.

But there’s a version of this where the defense becomes self-defeating. Investing to protect against inflation while simultaneously draining the cash buffer you’d need in an emergency isn’t defense. It’s just a different kind of vulnerability.

So am I NISA-broke or not?

Let me be direct.

The ¥210,000 monthly deficit is intentional. I’ve modeled when the cash hits the floor. I have a trigger point (¥5,000,000) where I’ll reduce contributions. I have ¥20M in unrealized gains as a secondary buffer. And I have 12 months of living expenses in cash.

Whether that counts as NISA-binbo depends on your definition.

Mine: the defining factor is whether it’s planned. If you don’t know when your cash runs out, if you can’t bring yourself to cut contributions even when cash is critically low — that’s the broke part. Not the percentage. Not the raw yen amount.

By that definition, I’m not NISA-broke. Not yet, anyway.

¥370,000 again next month

From the outside, investing 62% of your income probably looks unhinged. Zero regrets, though.

My wife runs her own NISA account her own way. We don’t push investment opinions on each other. My daughter is 8 and has no idea what I do with money — I’ve tried explaining and the response is “huh, cool” followed by immediate loss of interest. The household still functions. The bills get paid.

If I had to write a bio for myself: “Security industry salesperson, 62% investment rate.” Not information I’d put on a business card. But here we are.

¥370,000 next month. Same the month after. Until the cash hits ¥5,000,000, I’m not changing the number. In 19 months, I’ll write about what that actually felt like.

This article reflects personal experience and is for informational purposes only — not investment advice. All investment decisions are your own responsibility.