Liquidity, rate certainty, deposit insurance, inflation risk, early-withdrawal rules, and emergency-fund suitability.
Ordinary savings give instant access, time deposits fix a rate for a term, and retail JGBs add government-backed principal — all are low-risk stores of value with low returns, and all carry inflation risk; ordinary savings suit an emergency fund.
These three tools trade access for return in small steps. Ordinary savings give instant access with a stable balance but the lowest return. A time deposit locks your money for a term in exchange for a fixed, slightly higher rate — predictable, but with early-withdrawal restrictions or penalties. A retail JGB offers government-backed principal, a ¥10,000 minimum, and monthly issuance, redeemable after one year with a deduction of the previous two interest payments.
None of these is a growth investment. They are places to keep money safe and reasonably accessible, with the differences mostly in how quickly you can get it and how the rate is set.
Bank deposits are protected by deposit insurance up to ¥10m of principal per depositor per bank, plus accrued interest; certain non-interest settlement deposits get fuller protection, while foreign-currency deposits are generally outside ordinary coverage. Retail JGBs carry the government’s credit rather than deposit insurance. Spreading large balances across banks changes coverage.
All of these share one risk: inflation. Because their returns are low, rising prices can erode your real purchasing power even though the yen balance does not fall. That is fine for short-term and emergency money, which needs reliability more than growth, but it is why long-horizon money is usually invested rather than left entirely in cash.
An emergency fund needs reliability and instant access, so ordinary savings are the natural home — you must be able to reach the money the day you need it, without market risk or withdrawal penalties. A time deposit or JGB can hold money for a known future date (a planned purchase in a year or two) where you accept slightly less flexibility for a marginally better rate or government backing.
The rule is to match the tool to when you will need the money: instant-access savings for emergencies and near-term spending, time deposits or JGBs for known short-term goals, and investments only for money you will not touch for years.
Brokerage (NISA/iDeCo) · Rakuten Securities
A leading low-cost brokerage for NISA and index-fund investing, integrated with Rakuten points and Rakuten Bank.
Fees: Many domestic funds and trades are low- or no-commission — verify current fee schedule.
Brokerage (NISA/iDeCo) · SBI Securities
Japan’s largest online brokerage by accounts, with a very broad low-cost fund lineup and full NISA/iDeCo support.
Fees: Many trades and funds are low- or no-commission — verify current fee schedule.
Brokerage (NISA/iDeCo) · Monex
An established online brokerage often chosen for US-stock access and research tools, with NISA and iDeCo support.
Fees: Commissions vary by product; some funds/trades are low-cost — verify current schedule.
This is education, not a recommendation. Most beginners research low-cost, broadly diversified index funds — for example all-country (全世界株式) or S&P 500 trackers — rather than picking individual stocks, because low fees and diversification are within your control while returns are not. Understand that values fall as well as rise, match the risk to your time horizon, and never invest money you may need soon.