This article is written by a Japanese local.
Among foreign employees relocating to Japan, it is not uncommon for them to mistakenly believe, “Since I have calling apps like WhatsApp or LINE and a company landline, there is no need to go out of my way to contract a personal Japanese mobile number.”
However, in Japanese society, mobile phone numbers starting with “090, 080, or 070” function beyond a mere means of contact; they serve as an “ID (identification) that guarantees personal credibility.” Not possessing this number means that all legal, administrative, and financial procedures within Japan will physically come to a halt. This article objectively explains the legal background and practical importance of why possessing a mobile phone number is an “absolute requirement.”
1. The Wall of “Mandatory Input Fields” in Administrative and Financial Procedures
[Summary] A Japanese phone number is systemically mandatory when opening bank accounts or handling municipal procedures. Without it, procedures cannot begin.
From opening a “bank account” to receive a salary in Japan, to registering a “Certificate of Residence (Juminhyo)” or issuing a “My Number Card” at the municipal office, and even applying for a credit card, every public and semi-public application form contains a field for a “Japanese phone number where the individual can be reliably reached.”
Japanese financial institutions enforce strict KYC (Know Your Customer) policies to combat money laundering and terrorist financing (AML/CFT). Systemically, you cannot input overseas phone numbers (such as +1 or +86), and if the phone number field is left blank, the application will not even reach the screening stage.
2. Strict Screening by “Guarantor Companies” for Real Estate Rentals
[Summary] When renting an apartment, a mobile phone number registered in your own name is indispensable for the rent guarantor company’s screening process.
When renting an apartment in Japan, contracting with a “Rent Guarantor Company” instead of providing a joint guarantor is required almost 100% of the time. One of the most emphasized processes in the guarantor company’s screening is the step where they “call the mobile phone listed on the application to confirm whether the applicant answers (incoming call verification).”
At this time, it is generally unacceptable to register a “company main number” or an “HR representative’s number” as a proxy just because the employee does not have a personal number. If there is no phone number that directly connects to the individual, the guarantor company will automatically “reject” the application, making it impossible to secure housing.
3. The Limits of IP Phones (050) and the “Act for Prevention of Improper Use of Mobile Phones”
[Summary] Easily acquired “050” numbers have low credibility due to lax legal identification requirements, and they are rejected by financial institutions because they cannot receive SMS authentication.
Some foreigners attempt to substitute IP phone apps starting with “050,” which can be easily obtained via the internet, but this does not work in practice.
In Japan, mobile phone numbers starting with “090/080/070” are issued only after strict face-to-face or equivalent identity verification (matching the Residence Card with a facial photo) based on the “Act for Prevention of Improper Use of Mobile Phones.” Therefore, holding a 090/080/070 number carries a social guarantee that “this person has passed strict identity checks based on Japanese law.”
Conversely, 050 numbers are highly anonymous and have a history of being abused for crimes like fraud, so they are increasingly rejected systematically as registration numbers for banks and credit cards. Furthermore, 050 numbers cannot receive the “SMS (Short Message Service) authentication” one-time passwords essential for online banking, thereby failing to meet practical requirements.
4. Practical Q&A (Troubleshooting HR Should Guide)
[Summary] Answers questions directly related to HR operations, such as the compliance risks of lending a company number.
Q. To rush the procedure, is it okay to temporarily register the “company landline” or the “HR rep’s mobile number” as the employee’s contact info?
A. This is strictly prohibited. If you register a third party’s (company or HR) number with a bank or municipal office, all subsequent personal collections or privacy-related communications for that employee will go to the company. Additionally, if they forget to change the number upon resigning, the employee’s personal information remains tied to the company’s number, leading to serious compliance troubles.
Q. I understand a Japanese mobile number is essential. What is the fastest sequence to arrange it?
A. The fastest and legally correct route is as follows:
① Entry into Japan → ② Address registration at the ward office (address printed on the back of the Residence Card) → ③ Same-day contract for a “Low-Cost SIM (090/080/070)” using an overseas credit card → ④ Use that number to open a bank account and set up utilities.
Deviating from this sequence will result in a complete deadlock.
Conclusion: A Mobile Number is a “Passport” in Japanese Society
In modern Japanese society, a mobile phone number (090/080/070) functions as a “second passport” that proves an individual’s existence and credibility. HR managers must firmly make employees realize that it is not about the convenience of communication, but rather the “absolute ticket of entry” for legal and financial procedures, and strictly enforce front-loading to ensure they contract one immediately upon entry.