About four years ago I got a call from a neighbor of one of my units telling me a completely different person had been living there for almost two months. My actual tenant had quietly moved to Osaka for work and let a friend stay in the apartment, no notice, no request, nothing in writing. That single incident cost me about 3 weeks of back-and-forth with a lawyer and roughly 45,000 yen in consultation fees before it got sorted out. If you manage rental property in Japan long enough, you will eventually run into a tenant who wants to sublet, or who already has without asking.
Across my 9 properties I have now dealt with this situation five separate times, and each one taught me something different about how to respond without torching the relationship or losing the unit to someone I never screened.
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The core problem is not just that a stranger is in your property. It is that you now have zero legal relationship with the person actually living there. My standard lease (chintai keiyaku) has a clause requiring written landlord consent before any sublet or transfer of occupancy rights, and almost every standard Japanese residential lease has the same clause. When a tenant sublets without asking, they are in breach of contract, which under most agreements gives you grounds for termination. But termination is a last resort, not a first move, because eviction in Japan can take 6 to 12 months through the courts if the tenant does not leave voluntarily.
How I Usually Find Out
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In my experience it is almost never the tenant who tells you. It is a neighbor mentioning a new face, a different name on the mailbox, or a change in the parking registration. I now do a quick walk-by inspection of common areas once every 2 months on each property specifically to catch this early, because the earlier you catch it, the fewer months of unpermitted occupancy you have to untangle.
What the Lease and the Law Actually Say
Under Japan’s Civil Code, a tenant generally needs the landlord’s consent to sublet or assign the lease to someone else. Without that consent, the landlord can request termination of the head lease, though courts have sometimes protected tenants when the breach was minor or there was a reasonable relationship of trust with the sub-occupant. That last part matters. If your tenant sublet to a close family member and paid rent on time every month for a year, a judge may be less sympathetic to an eviction than if they sublet to a stranger through a listing site while collecting a markup. I always factor that distinction into how hard I push.
My Step-by-Step Response
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Here is the process I have refined after going through this five times:
- Document everything first. Photos of mail, names on the intercom, dates of when you first noticed.
- Contact the original tenant directly, calmly, and in writing (email plus a follow-up call). Ask them to explain the situation rather than accusing them immediately.
- Reference the specific clause number in the lease that requires consent, so there is no ambiguity about the violation.
- Offer a path forward: either the original tenant resumes occupancy within 2 weeks, or you formally screen and approve the sub-occupant with an updated lease and a new deposit equal to one month’s rent.
- If the tenant refuses to cooperate or cannot be reached within 10 days, send a formal notice through a judicial scrivener (shiho shoshi), which in my area runs about 30,000 to 50,000 yen and creates a paper trail for eventual court action if needed.
- Loop in your guarantor company (hoshonin gaisha) immediately if you use one, since many of them will step in and cover unpaid rent during a dispute like this.
When I Actually Say Yes
Two of my five sublet situations ended with me approving the arrangement. In both cases the sub-occupant had stable income, passed the same screening I use for new tenants (income at least 3 times the monthly rent, a valid guarantor, no history of rent delinquency), and the original tenant agreed to remain financially responsible as a co-signer for another 6 months. When those conditions are met, approving the sublet is often less disruptive than forcing a vacancy, especially in a building where I was already sitting on a 2-month vacancy on another unit and did not want a third.
Preventing the Next One
Since that first incident, I added a specific line to every lease I sign stating that any unapproved occupant discovered on the property triggers an immediate rent increase of 20 percent for the remainder of the lease term or termination, landlord’s choice. I also started including a photo ID requirement for anyone listed as an approved additional occupant, updated every time the lease renews. It has cut my repeat incidents from about one every 18 months down to zero in the last 2 years.
Handling this well is mostly about staying calm, moving fast on documentation, and knowing which battles are worth fighting versus which arrangements are actually fine once you screen the new occupant properly. That is the balance I try to strike across all 9 of my properties.
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