Sublet a Tokyo apartment: what Article 612 decides

民法第612条 (minpō dai-612-jō — Civil Code article 612) is two sentences long, and the second one ends your lease.

Here is the whole article, from the e-Gov statute database:

賃借人は、賃貸人の承諾を得なければ、その賃借権を譲り渡し、又は賃借物を転貸することができない。

賃借人が前項の規定に違反して第三者に賃借物の使用又は収益をさせたときは、賃貸人は、契約の解除をすることができる。

In English: a tenant may not transfer the lease or sublet the property without the landlord's 承諾 (shōdaku — consent). If the tenant lets a third party use the property in breach of that, the landlord may cancel the contract.

Read the second sentence again. It does not fine you. It does not void the sublease. It hands the landlord the right to end the lease you signed, which is the thing you were trying to hold on to.

That sentence sits underneath every sublet offer you see in a Tokyo expat Facebook group or on a message board.

Two people arrive at the same search from opposite ends. One is a foreign tenant on a two-year lease, away for three to six months, who does not want to pay for an empty apartment. The other wants somewhere to live for a few months and thinks they have found a cheap way. Article 612 does the same thing to both. The tenant risks the lease. The person who moves in loses the apartment on the same day, because their right to be there comes out of that lease and cannot outlast it.

This is why the informal sublet market in Tokyo stays small. It is not enforcement pressure or platform policy. The downside is the whole tenancy, and it falls on the person with the most to lose.

There is a real limit on that power. Japanese courts do not treat every unconsented sublet as grounds to cancel. The Supreme Court held on 25 September 1953 that where special circumstances mean the tenant's act cannot be treated as a 背信的行為 (haishinteki kōi — an act of betrayal, a break in the trust between the two parties), the landlord cannot cancel under article 612(2). The 全日本不動産協会 (Zennichi — the All Japan Real Estate Association) states the holding this way:

賃借人が賃貸人の承諾なく第三者をして賃借物の使用・収益をなさしめた場合でも、賃借人の当該行為を賃貸人に対する背信行為と認めるに足りない特段の事由があるときは、賃貸人は、本条（民法第612条）2項により契約を解除することができない。

Look at the cases that fit. A tenant running a shop out of the building sets up a company, and the company then uses the same space. A lease moves from husband to wife at divorce. What those share is that almost nothing changed: same use, same people, nobody new for the landlord to deal with.

Renting your apartment to a stranger for four months at ¥170,000 a month is the opposite shape. New occupant, money changing hands, and someone living in the landlord's building the landlord never agreed to. That is the kind of case the rule was written to separate out, not the kind it protects.

The rule is a defence, not a permission. You raise it after the landlord has moved to cancel, in front of a judge, and proving the special circumstances is your job. It is what you argue about once skipping the conversation with your landlord has gone wrong.

Put numbers on the trade, because it is smaller than it looks.

Assume a one-bedroom in Nakano on a two-year lease at ¥150,000 a month, and a sublet at ¥170,000 because it comes furnished and month to month.

Three months away: the sublet is worth ¥510,000 to you. That is ¥450,000 of rent you owe whether anyone is living there or not, plus ¥60,000 on top.

Six months away: ¥1,020,000 on the same arithmetic.

Now the other side. If the lease ends you have to secure another one, and moving into a Japanese apartment costs most of its money on the first day.

• 礼金 (reikin — "gratitude money," a non-refundable payment to the landlord at signing). One month, so ¥150,000. The Ministry of Land, Infrastructure, Transport and Tourism's FY2024 housing market survey found 42.6% of private-rental households paid reikin, and that where it was paid, 65.0% paid exactly one month. Furnished mid-term stays dropped it for reasons of their own.
• 敷金 (shikikin — "deposit money," returned at the end of the lease minus restoration costs). One month, so ¥150,000. The same survey puts this at 57.7% of households, 61.7% of them paying exactly one month. Most of it comes back, so count it as cash you must produce rather than cash you lose.
• 仲介手数料 (chūkai tesūryō — the agent's brokerage fee). ¥165,000. This one has a legal ceiling. The ministry notice that sets broker pay (建設省告示第1552号, amended in 2024) caps the total on a residential lease at 1.1 times one month's rent including consumption tax, and caps your own side at 0.55 months unless you agreed otherwise when you hired the agent.
• Guarantor company, first-year fee. Around 50% to 100% of one month's rent, so ¥75,000 to ¥150,000. Call it ¥112,500. What these companies do is worth reading first.
• Moving. Assume ¥60,000 for a small Tokyo move and put your own quote in its place.

Non-refundable total: ¥487,500. Cash you need on the day, deposit included: ¥637,500.

At three months, then, you are putting ¥487,500 at risk against ¥510,000 of benefit. That is close to even money. At six months the ratio improves to roughly two to one, because the downside does not grow with the length of the sublet and the upside does. It explains why the informal offers you see tend to run long rather than short.

Money is not the whole downside. You also lose the apartment, and you apply for the next one from wherever you are, with a guarantor company reading your file and a landlord asking why the last lease ended early.

Two workarounds get suggested a lot. Both run back into the same requirement.

The first is a condominium's own rules. If your building is one, the 管理規約 (kanri kiyaku — the management rules the owners' association votes on) can prohibit paying guests by itself, whatever your landlord thinks. That is a second consent, checked separately.

The second is registering the place as a minpaku. 住宅宿泊事業法 (jūtaku shukuhaku jigyō-hō — the Housing Accommodation Business Act, the 2018 private-lodging law) lets a residence take paying guests after a notification to the prefectural governor. Read the ministry's list of documents that notification needs and item 8 is 「賃借人の場合、賃貸人が承諾したことを証する書類」: if you are a tenant, a document proving the landlord consented. The portal adds that it has to say in so many words whether running a lodging business is allowed. Item 10 asks for a copy of the condominium rules too.

The minpaku route does not get you around consent. It asks for the same consent in writing before you may register, then caps you anyway. Article 2 defines the business as one where the nights of accommodation come to 「一年間で百八十日を超えない」, not more than 180 days in a year. Over a four-month absence that ceiling is not what stops you. The consent is. What the cap does to prices and which statute governs a given stay are separate questions. If you are offered a registered minpaku, the M-number lookup checks it in about thirty seconds.

The furnished mid-term apartment is this same transaction with the consent already done.

An operator's apartment is a sublet. You are renting not from the owner but from a company that holds a long-term lease on the unit, doing the exact thing article 612 restricts. The difference is that their lease was written with the sublease permission inside it, agreed with the owner before a single guest arrived. Master-lease economics walks the money up that chain. The legal content is one clause.

That clause is the product. Not the furniture, not the flexible dates. Those are downstream. What the operator sells is permission that already exists, which is why they can hand you a contract without phoning anybody. What you sign is usually a fixed-term lease under a different statute, and teiki-shakka has its own trade-offs.

For the tenant with the empty apartment, the move is to ask. A 承諾書 (shōdakusho — a written consent document) from your landlord costs a conversation and sometimes a fee, and it turns the whole problem into paperwork. Many landlords say no. A no is cheap to get, and much cheaper than the arithmetic above.

For the person being offered a sublet, the risk has nothing to do with whether the other person seems trustworthy. It is about whether a document exists. Three questions get you there:

• Who holds the lease on this apartment, and are they the owner or a tenant?
• Is there written consent to sublease, and may I see it?
• What am I signing, and whose name is on the other side?

An offer that answers all three is an ordinary rental with an unusual length. An offer that goes quiet on the second one is a lease that can end at the owner's choice, on a timetable neither of you controls.

So the question to ask about a Tokyo sublet is not what it costs a month. It is whether a piece of paper exists with the owner's name on it. If it does, you are signing a contract. If it does not, you are living in an apartment the owner can take back, and article 612 is the sentence they will use to do it.

— HalfKey runs furnished Tokyo apartments under master leases with the owners, for stays of 30 days to 12 months. Browse listings for your dates.