How Loan Repayments Work in Japan

Every loan in Japan — a bank card loan, a car loan, a housing loan — is the same machine under different labels: a balance, a rate, and a schedule of payments that extinguishes the balance. Understand the machine once and every offer you ever see becomes readable. This guide walks through how Japanese lenders actually structure repayments, how they count the days, and where the traps sit.

The standard structure: equal instalments (元利均等返済)

Most Japanese consumer loans and mortgages repay by genri kintō hensai — equal instalments of principal and interest. Each month's payment is the same number from the first to the last, but its composition shifts constantly: early payments are mostly interest, late payments are mostly principal. On a ¥1,000,000 loan at the illustrative 8% rate over 3 years, the instalment is about ¥31,300; the first payment includes roughly ¥6,700 of interest, while the final one carries almost none. The balance therefore falls slowly at first and fast at the end — which is why early extra payments save so much interest: they attack the balance while it is still large.

The rarer alternative, gankin kintō (元金均等， equal principal), repays the same slice of principal every month plus that month's interest, so payments start high and fall steadily. Banks rarely offer it on consumer loans, but you will meet it on some housing loans and school instalment plans. Total interest is lower than the equal-instalment structure at the same rate and term, because the principal falls faster — the honest price of that saving is the higher early payment.

How Japanese lenders count interest: the daily balance

Japanese lenders typically calculate interest on the daily outstanding balance (日割り計算)， not in monthly lumps. The annual rate is divided down to a per-day figure, applied to whatever you owe each day, and the month's interest is summed and added to your next payment. Two practical consequences follow. First, paying early in the month instead of late genuinely reduces the interest charged for that month on many products. Second, overpayments reduce interest from the day they land, not from the next scheduled review — the reason extra payments are the cheapest debt tool most borrowers never use.

Payment dates are usually a fixed day each month (often the end of month or a day you chose at contracting), with interest counted over the days since the last payment. On housing loans, the first payment often falls a month or two after disbursement, and the odd first period — longer or shorter than a standard month — is charged accordingly. None of this changes the arithmetic; it only shifts a few hundred yen here and there.

Where the structure differs by product

• Housing loans (住宅ローン): equal instalments, optionally split into a monthly portion and a bonus portion (ボーナス返済) repaid in two larger instalments a year. The bonus portion accrues interest for the six months between payments — see the mortgage calculator for the full model.
• Car loans (マイカーローン): plain equal instalments on the financed amount; taxes and fees usually stay outside the loan. The car loan calculator shows the all-in cost.
• Card loans (カードローン): revolving credit with a minimum monthly payment that often covers little beyond interest. A balance can survive indefinitely at the minimum — the structure is designed to keep you paying, not to finish.
• Credit card instalments (分割払い) and revolving (リボ払い): instalment plans add a monthly fee to each payment; revolving carries a rate on the surviving balance. Both are priced in the credit card & instalment calculator.

Paying early, and what to compare

Early and extra repayment are permitted on most Japanese loan products, and because interest accrues on the daily balance, the saving is real and immediate. Some products carry conditions or procedural steps — confirm with your lender before assuming. Never pay an upfront "arrangement fee" to anyone for the privilege of repaying your own debt; that is a broker's fee, not the lender's.

When comparing two offers, the only fair metric is total repayment at the same term — the sum of every payment you would make. The headline rate can mislead (fees hide in it), and the monthly instalment can mislead worse, because a longer term shrinks the payment while growing the total. Run any offer through the personal loan calculator before signing, and read the companion guide on how interest is charged in Japan for the rate side of the picture.