Best Investment Account for Beginners in Japan: NISA vs. iDeCo vs. Regular Brokerage

If you have just arrived in Japan — or have lived here for years but never gotten around to investing — the first question is always the same: which account should I open first?

Japan offers three main account types for retail investors: the tax-advantaged NISA, the pension-focused iDeCo, and a plain taxable brokerage account. Each serves a different purpose, and picking the wrong one first can cost you years of compound growth or lock away money you actually need.

This guide explains all three side by side, walks you through a decision flowchart, simulates 20-year growth in each account, and then shows the exact steps to open a Rakuten Securities account with your My Number card.

1. Three Account Types Explained Side by Side

NISA (Nippon Individual Savings Account)

NISA is Japan’s flagship tax-free investment wrapper, redesigned and made permanent in 2024. The key benefit is simple: all capital gains and dividends earned inside NISA are completely tax-free. In a regular account you would pay 20.315% on every yen of profit; inside NISA, that tax disappears entirely.

One important nuance: when you sell investments inside NISA, the “used” lifetime allowance is restored the following year. This means your ¥18M lifetime cap is not a one-way door — it replenishes over time as you sell, giving you long-term flexibility.

iDeCo (Individual Defined Contribution Pension)

iDeCo is Japan’s self-directed pension scheme. It comes with two tax benefits stacked on top of each other: contributions are fully tax-deductible (reducing your income tax and residence tax each year) and all investment growth is tax-free while the money remains in the account.

The trade-off is liquidity. Money inside iDeCo is locked until age 60 — no exceptions. If you withdraw early due to financial hardship, the rules are extremely strict and withdrawals are generally not permitted until the minimum age requirement is met.

The contribution deduction is genuinely powerful. An employee earning ¥6M annually and contributing the maximum ¥23,000/month (¥276,000/year) would save roughly ¥55,000–¥83,000 per year in taxes depending on their marginal rate. Self-employed individuals contributing ¥68,000/month save even more.

Regular Taxable Brokerage Account (Tokutei Koza)

A standard brokerage account in Japan — called a tokutei koza (特定口座) with “withholding” selected — has no contribution limits and no restrictions on withdrawal, but all profits are taxed.

The 20.315% effective rate means that for every ¥100,000 profit, you hand ¥20,315 to the government. Over a 20-year compounding period, this drag is substantial — which is why most beginners should exhaust their NISA room before using a taxable account.

At-a-Glance Comparison Table

2. Decision Flowchart: Which Account Should You Open First?

Work through these questions in order.

Step 1: Do you have an emergency fund? Before investing anything, you need 3–6 months of living expenses in a liquid savings or high-yield deposit account. If not, build that first. No flowchart needed.

Step 2: Are you employed and does your employer offer a corporate DC (企業型DC) plan? If yes, check whether your employer allows simultaneous iDeCo contributions. As of 2022, most employees can join iDeCo even with a corporate DC, but the combined limit applies. Confirm this with your HR department first.

Step 3: Do you have stable income and won’t need this money before age 60?

• Yes, and you pay income tax: Open iDeCo first for the contribution deduction, then NISA. The deduction gives you an immediate return on top of investment growth.
• No — you might need the money before age 60: Skip iDeCo for now. Open NISA first. Full liquidity at zero tax cost is the priority.

Step 4: Have you maxed out your NISA for the year?

• If you still have NISA room: put new money there before any taxable account.
• If NISA is full and you have more to invest: open a regular tokutei koza.

The most common beginner path: NISA first → iDeCo second (for the tax deduction) → taxable account only if both are maxed.

Self-employed (freelancer / sole proprietor): iDeCo first. The ¥68,000/month deduction (¥816,000/year) is one of the largest legal tax reduction tools available to you. Then NISA.

Part-time worker or low income (below the income tax threshold): NISA only. The iDeCo deduction has no value if you are not paying income tax.

3. Simulating 20-Year Growth Across Each Account Type

Let’s make this concrete. Suppose you invest ¥30,000 per month (¥360,000/year) for 20 years into a broad global index fund averaging 5% annual growth.

Base Assumptions

Scenario A: NISA Account

Inside NISA, every yen of growth is tax-free. After 20 years:

• Final portfolio value: approximately ¥12,330,000
• Tax owed on withdrawal: ¥0
• Net gain over contributions: approximately ¥5,130,000

The entire ¥5.13M gain is yours to keep.

Scenario B: Regular Taxable Account

In a taxable account, the 20.315% rate applies to all realised gains at withdrawal. Using a simplified end-of-period tax calculation:

• Gross portfolio value: approximately ¥12,330,000
• Capital gain: approximately ¥5,130,000
• Tax on gain (20.315%): approximately ¥1,042,000
• Net after-tax value: approximately ¥11,288,000

You lose approximately ¥1,042,000 to tax compared to NISA — purely because of account choice.

Scenario C: iDeCo Account (Employee, ¥23,000/month)

iDeCo’s monthly limit for employees is ¥23,000, so this scenario uses ¥23,000/month (¥276,000/year).

• Final portfolio value: approximately ¥9,475,000
• Tax owed: deferred until payout (lump-sum deduction applies — first ~¥15M is tax-free under retirement income deduction for 20+ years)
• Annual tax saving during accumulation (at 20% marginal rate): approximately ¥55,200/year = ¥1,104,000 over 20 years

The iDeCo comparison is more complex because the deduction savings compound in your other investments, and the retirement income deduction largely shields the payout. For most middle-income employees, iDeCo + NISA together handily beats NISA alone.

Walk Through the NISA Simulator

You can model your own numbers using the NISA Simulator on this site. Here is the exact process:

1. Open the NISA Simulator .
2. Enter your monthly investment amount — for example, ¥30,000.
3. Set the expected annual return — 5% is a reasonable long-run assumption for a diversified global equity index fund, but you can test 3%, 5%, and 7% scenarios.
4. Set the investment period in years. Try 20 years, then adjust for your actual retirement timeline.
5. The simulator shows your final NISA balance alongside a taxable account scenario, so you can see the exact yen difference tax-free compounding makes.
6. Click “Compare with iDeCo” to run a parallel iDeCo projection. Enter your monthly contribution limit and marginal tax rate.

Also try the iDeCo Simulator to model the tax-deduction savings year by year, and the Compound Interest Calculator to experiment with different return assumptions.

For a full picture of how these accounts feed into retirement, the Retirement Calculator lets you combine your NISA, iDeCo, and public pension (nenkin) into a single retirement income projection.

4. Opening a Rakuten Securities Account: Exact Steps for Residents with a My Number Card

Rakuten Securities (楽天証券) is one of Japan’s two largest online brokers alongside SBI Securities. It offers a clean interface in both Japanese and partial English, integrates with Rakuten Bank for easy cash transfers, and covers both NISA and iDeCo in the same login.

What you need before you start:

• My Number card (個人番号カード) — the physical card with the IC chip, not the paper notification slip
• Your smartphone with NFC capability (for card scanning)
• Japanese bank account or Rakuten Bank account
• Registered address in Japan (juusho)
• Email address

Step-by-Step Account Opening

Step 1: Go to the Rakuten Securities application page. Visit rakuten-sec.co.jp and click “口座開設” (Open an Account). You can also apply via the Rakuten Securities app.

Open a Rakuten Securities account and start investing tax-free: Apply via Rakuten Securities affiliate link

Step 2: Enter your basic information. Fill in your name (exactly as it appears on your residence card or My Number card), date of birth, address, phone number, and email address. For foreign residents, use your registered address exactly as filed with your local municipal office.

Step 3: Select your account types. You will be asked which accounts to open simultaneously. Select:

• Tokutei koza (特定口座) with withholding (源泉徴収あり) — this automates your tax reporting
• NISA account — check the box to apply for NISA at the same time
• Optionally: iDeCo can be added later from the member portal

Step 4: Identity verification with your My Number card. Choose “My Number card” as your identity document. The app will prompt you to:

1. Photograph the front of your My Number card
2. Scan the IC chip via NFC (hold the card to the back of your phone)
3. Enter your 4-digit My Number card PIN (the one you set at the municipal office)

This e-KYC process typically completes in minutes. If you do not have a My Number card, you can use a combination of your residence card and a bank statement, but the process takes longer (postal verification).

Step 5: Fund your account. Once approved (usually 1–3 business days), log in and link your bank account. Rakuten Bank users get zero-transfer-fee top-ups and a higher savings interest rate when both accounts are linked (Maneo Program). Set up a monthly auto-sweep to automate your NISA contributions.

Step 6: Choose your first fund. For most beginners, a single all-world index fund is the simplest and most evidence-based starting point. Search for “eMAXIS Slim 全世界株式” (eMAXIS Slim All Country) in the fund search. It has a very low annual cost (TER around 0.057%) and covers over 2,800 companies across 47 countries.

Set up a monthly automatic purchase (積立設定) aligned with your NISA tsumitate limit. Done.

Key Takeaways

• NISA is the default first account for most residents — zero tax on growth, fully liquid, up to ¥3.6M/year.
• iDeCo is powerful if you pay income tax and can commit money until age 60 — the deduction gives you an instant return before any market movement.
• Regular brokerage is for overflow once you have maxed NISA; the 20.315% tax drag is real over 20+ years.
• The 20-year simulation shows roughly ¥1M in tax savings just by using NISA instead of a taxable account on the same ¥30,000/month plan.
• Open a Rakuten Securities account with your My Number card — the e-KYC process takes under 10 minutes.

Run your own numbers with the NISA Simulator , the iDeCo Simulator , and the Retirement Calculator before you decide on a contribution amount.

Ready to start? Open a Rakuten Securities account today: Apply for a Rakuten Securities Account

Related Tools

Calculate compound interest → Compound Interest Calculator Plan your retirement → Retirement Calculator Estimate your tax bracket → Tax Bracket Calculator See how inflation affects your money → Inflation Calculator

Disclaimer

This article contains affiliate links. If you open an account via the links on this page, we may receive a commission at no extra cost to you. All opinions are our own. This article is for informational purposes only and does not constitute investment advice. Investment returns are not guaranteed, and the value of your investments can go down as well as up. Tax rules described reflect Japanese tax law as understood in May 2026 — always verify current rules with a tax professional or the NTA (国税庁) website before making decisions. iDeCo rules and contribution limits are subject to change.

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