There are more resources on the internet now for accessing and applying for financial products in Japan. If you have a qualifying visa and residence in Japan, whether you are staying for 1-3 years or longer, you can apply for these products or in some cases, you will be automatically enrolled as a condition of your employment. Once you've received your visa, applied for your residence card and your "my number card", you can sign up or apply for, or be enrolled for financial services.
You'll need a bank account for most jobs to receive your salary. For some small businesses, they might prefer to pay you in cash at the end of the month, but most if not all jobs will ask for your bank account details to send you money.
One program from the SWIMMY channel on Youtube is a good overview
Life Insurance in Japan has many companies offering products like term life and whole life policies for individuals. You might also be enrolled in a life insurance policy at work if you die in the course of your work, so it is good to check with your employer. Life insurance policies are probably exclusively in Japanese though, as they are sold under Japanese law, and documentation in other languages will be rare. If you speak and read Japanese or have a family member who does, then you can look at the choices available via an insurance broker or on the web directly. There are threads on discussion boards like Reddit that address this.
As the documentation for insurance products is very precise, and in Japan, the standards for details and where to stamp seals for approvals very strict, be prepared for the application process to take a while. Time and patience are good things to have considering any errors that could happen in terms of the application or just the time it takes to fill out the form, even with an agent's assistance.
Cancer insurance is a type of policy available in Japan, and foreign insurers are active in this market. AFLAC pioneered the market in Japan. An interesting overview of the health insurance market in Japan is here from Internations.
Here is a good story of AFLAC and Japan.
However, for this insurance, there is still the certainty that all the forms are in Japanese, unless you make a contract with an overseas provider.
Home insurance is typically included in or sold with apartment lease contracts in Japan and can cover fire insurance and earthquake insurance. Here is a explanation from Plaza Homes in Tokyo.
First month’s rent = ¥60,000
Deposit (one to two month’s rent) = ¥60,000 to ¥120,000
Key money (one to two month’s rent) = ¥60,000 to ¥120,000
Agent’s commission (one month’s rent + tax) = ¥64,800
Guarantor company fee (one month’s rent + tax) = ¥64,800
Property maintenance fee = ¥3,000 to ¥5,000
Renters/Fire insurance = ¥20,000 (for a two-year policy)
Lock exchange fee = ¥12,000
Getting a credit card in Japan is easier the longer you are working here, since the credit bureau can check job history, and use other factors to like bank accounts or other records to assess credit risk.
While the applications will be in Japanese, either online or via the mail, there is a lot of information on which cards to choose online in English. Here is one site recommending cards in Japan for foreigners.
Looking at the statistics from the Japan Consumer Credit Association, there is a steady growth in the number of credit cards being issued which means to maintain the growth, issuers are more comfortable with evaluating many different types of consumer profiles, including foreign residents.
There are educational loans available for some secondary education, such as international schools, as well as to go to universities in Japan or overseas. Temple Japan has a list here of different sources of aid to attend their institution as an example. While the number of foreigners who might want to access the loans is smaller compared to the population, they are a good option if you want to finance your own education or as a parent wanting a loan for their children's education because Japan's interest rates are typically lower than those in other countries. There is a cap on the total amount that can be loaned based on your income, or a total cap on the amount of loans that can be given under low-interest loan programs.
As with the other financial services, the applications will be in Japanese, and the amount of paperwork will involve details on the school to be attended, along with tuition, and other loans currently outstanding. But there will be support from the bank extending the loans, so as long as you have the time for the application and the relevant details, then the process to apply can be smooth.
Another category of loans in Japan would be consumer loans, which are cash loans that are limited to an annual interest rate of 18%. These are offered by a wider range of financial institutions that have bought, partnered or opened up units specifically to make these types of no-collateral loans. These loans are unsecured and can be bundled with credit cards, so that credit is divided between "shopping" credit limits and "cashing" credit limits. The cashing limit can be raised over time, but the interest rate rarely changes. You can apply for other cards, in order to retire higher-interest loans from other providers and cut your interest rate by several percentage points. While the application and credit check can be done online, it is Japanese-only for the major providers.
There is the national health insurance scheme in Japan, which everyone has to join. There are different systems covering regular employees, unemployed individuals, and other categories of residents in Japan but Japan mandates coverage. That said, you can check with your employer about your health insurance and the fees deducted from you salary to understand what system you are covered by, and if you can switch. There are private insurance plans that are meant to reduce the cost of health insurance for foreigners, but the Japanese government and local authorities attempt to sign up all residents to the National health scheme if they don't belong to a corporate health plan or some other approved body.
Loans to buy property in Japan have been some of the most open to foreign residents I would say, because there are Japanese intermediaries who are involved in the building, sales and financing of residential homes who benefit from a fair process. So some of the best information in English on property loans and mortgages are to be found on real estate brokerage websites that cater to the foreign community in Tokyo, but it has a good overview of the loan options that are available in real estate financing in Japan.
With at least two loan providers aiming to lend to foreign residents in Japan, there can be options for getting a loan in English, but the majority of the banks will process all the loan applications in Japanese. However, many real estate agents and sales agents will have ties to banks and can introduce you to lenders who would lend up to between 85% to 95% of the real estate purchase price. The amount depends on the age of the building and an independent evaluation, as well as an assessment of the credit risk, but the loan would be backed by the underlying property collateral so it can be a relatively low interest rate.
Tofugu, a website about Japan and learning Japanese, has a good explanation about retiring here. IDeCo is the 401k or IRA-like program that allows tax free investment. There is another program modeled on the UK's Individual Savings Accounts called NISA which offers tax-free capital gains on investment over 5 or 20 years. These are meant to supplement the regular pension for people. They can be signed up for with most financial institutions like banks and securities companies, but there might be additional paperwork for reporting requirements if you are a foreigner, depending on your home country's laws.
Japan has a national pension system which relies on deductions from enrollees salaries and paid-in contributions from individuals, organizations and companies. Wikipedia has a short entry in English, mostly explaining the system and how contributions can be withdrawn from it by foreign residents. One private school mutual aid organization has a good explanation in English for its members of the pension system and how it affects academic employees at private schools who are enrolled in the system.
You get a breakdown of your pension contributions on your birthday every year mailed to you at your address. If you leave Japan, you can withdraw up to 3 years of your contributions in a lump sum.
Securities Trading Account
Opening up a Securities Trading Account with an Online Brokerage or a Securities company in Japan will be similar to opening up other financial accounts, except that there might be extra reporting requirements if you are American. For other nationalities, I haven't heard of the reporting requirements but most securities brokers will ask if new customers are American due to compliance reasons. After opening an account, you can choose to trade in a variety of financial instruments, like FX, Foreign Stocks, Futures & Options, and even Cryptocurrencies.
Cryptocurrency trading is relatively new in that it has had a popular reception in Japan among some people, and is home to some of the leading regulations for cryptocurrency, as well as important exchanges to trade them. A good history in English is here.
The Japan tax rules are covered here, while you just need to check with you home country if there are any reporting requirements there.