# Assert against (対抗, たいこう) This is the Markdown twin of https://japanlaw.org/en/concepts/assert-against. Every law, and how to address a provision: https://japanlaw.org/llms.txt. The same laws as MCP tools (no sign-in): https://japanlaw.org/mcp. - Group: Rights, roles and legal effects - URL: https://japanlaw.org/en/concepts/assert-against - In Japanese: https://japanlaw.org/ja/concepts/assert-against - Written by: claude-opus-5-5, 2026-09-23 To be able to rely on a right, or on a fact about it, against someone who is not a party to it. Acquiring, losing or changing a right in rem (物権) in land or a building cannot be asserted against third parties until it is registered (登記) (Civil Code, Article 177), and a registered lease of land or a building can be asserted against a person who acquires a right in rem in it, such as a buyer, and against other third parties (Article 605). The Act on Land and Building Leases lets a tenant do without registering the lease itself: a right to use land for a building (借地権) can be asserted against third parties once the tenant owns a registered building on the land (Article 10, paragraph (1)), and a building lease takes effect against anyone who later acquires a right in rem in the building, such as a new owner, once the building has been handed over (Article 31). Some rules protect only a third party who did not know: a rescission for fraud cannot be asserted against a third party who did not know of the fraud and was not careless in not knowing (善意でかつ過失がない) (Civil Code, Article 96, paragraph (3)). Written for this site by an AI model from the provisions and pages it cites. Each sentence was checked against them by a separate AI model run and revised to its findings. Not reviewed by a lawyer. ## Provisions and sources it draws on - [Civil Code, Arts. 96, 177, 605](https://laws.e-gov.go.jp/law/129AC0000000089) — on this site: https://japanlaw.org/en/civil-code - [Act on Land and Building Leases, Arts. 10, 31](https://laws.e-gov.go.jp/law/403AC0000000090) — on this site: https://japanlaw.org/en/land-and-building-leases-act ## Where the laws use it 15 laws in force use it in this sense, in 132 provisions; there the word opens this explanation. - [Civil Code (民法)](https://japanlaw.org/en/civil-code): 52 provisions, among them [Article 37](https://japanlaw.org/en/civil-code/art-37), [Article 93](https://japanlaw.org/en/civil-code/art-93), [Article 94](https://japanlaw.org/en/civil-code/art-94) - [Companies Act (会社法)](https://japanlaw.org/en/companies-act): 28 provisions, among them [Article 11](https://japanlaw.org/en/companies-act/art-11), [Article 14](https://japanlaw.org/en/companies-act/art-14), [Article 34](https://japanlaw.org/en/companies-act/art-34) - [Financial Instruments and Exchange Act (金融商品取引法)](https://japanlaw.org/en/financial-instruments-and-exchange-act): 10 provisions, among them [Article 29-4](https://japanlaw.org/en/financial-instruments-and-exchange-act/art-29-4), [Article 77-5](https://japanlaw.org/en/financial-instruments-and-exchange-act/art-77-5), [Article 79-24](https://japanlaw.org/en/financial-instruments-and-exchange-act/art-79-24) - [Civil Enforcement Act (民事執行法)](https://japanlaw.org/en/civil-enforcement-act): 8 provisions, among them [Article 55](https://japanlaw.org/en/civil-enforcement-act/art-55), [Article 59](https://japanlaw.org/en/civil-enforcement-act/art-59), [Article 64-2](https://japanlaw.org/en/civil-enforcement-act/art-64-2) - [Act on Building Unit Ownership (建物の区分所有等に関する法律)](https://japanlaw.org/en/building-unit-ownership-act): 7 provisions, among them [Article 4](https://japanlaw.org/en/building-unit-ownership-act/art-4), [Article 26](https://japanlaw.org/en/building-unit-ownership-act/art-26), [Article 46-3](https://japanlaw.org/en/building-unit-ownership-act/art-46-3) - [Copyright Act (著作権法)](https://japanlaw.org/en/copyright-act): 5 provisions, among them [Article 63-2](https://japanlaw.org/en/copyright-act/art-63-2), [Article 64](https://japanlaw.org/en/copyright-act/art-64), [Article 77](https://japanlaw.org/en/copyright-act/art-77) - [Bankruptcy Act (破産法)](https://japanlaw.org/en/bankruptcy-act): 4 provisions, among them [Article 56](https://japanlaw.org/en/bankruptcy-act/art-56), [Article 78](https://japanlaw.org/en/bankruptcy-act/art-78), [Article 93](https://japanlaw.org/en/bankruptcy-act/art-93) - [Act on Land and Building Leases (借地借家法)](https://japanlaw.org/en/land-and-building-leases-act): 3 provisions, among them [Article 10](https://japanlaw.org/en/land-and-building-leases-act/art-10), [Article 34](https://japanlaw.org/en/land-and-building-leases-act/art-34), [Article 38](https://japanlaw.org/en/land-and-building-leases-act/art-38) - [Act on Public Consultants on Social and Labour Insurance (社会保険労務士法)](https://japanlaw.org/en/labor-and-social-security-attorney-act): 3 provisions, among them [Article 25-10](https://japanlaw.org/en/labor-and-social-security-attorney-act/art-25-10), [Article 25-15-2](https://japanlaw.org/en/labor-and-social-security-attorney-act/art-25-15-2), [Article 25-31](https://japanlaw.org/en/labor-and-social-security-attorney-act/art-25-31) - [Labor Union Act (労働組合法)](https://japanlaw.org/en/labor-union-act): 2 provisions, among them [Article 11](https://japanlaw.org/en/labor-union-act/art-11), [Article 12-3](https://japanlaw.org/en/labor-union-act/art-12-3) - [Medical Care Act (医療法)](https://japanlaw.org/en/medical-care-act): 2 provisions, among them [Article 43](https://japanlaw.org/en/medical-care-act/art-43), [Article 46-6-2](https://japanlaw.org/en/medical-care-act/art-46-6-2) - [Act on General Rules for Application of Laws (法の適用に関する通則法)](https://japanlaw.org/en/application-of-laws-act): 2 provisions, among them [Article 9](https://japanlaw.org/en/application-of-laws-act/art-9), [Article 26](https://japanlaw.org/en/application-of-laws-act/art-26) - [Act on Specified Commercial Transactions (特定商取引に関する法律)](https://japanlaw.org/en/specified-commercial-transactions-act): 2 provisions, among them [Article 9-3](https://japanlaw.org/en/specified-commercial-transactions-act/art-9-3), [Article 58-14](https://japanlaw.org/en/specified-commercial-transactions-act/art-58-14) - [Road Transport Vehicle Act (道路運送車両法)](https://japanlaw.org/en/road-transport-vehicle-act): 2 provisions, among them [Article 5](https://japanlaw.org/en/road-transport-vehicle-act/art-5), [Article 76-7](https://japanlaw.org/en/road-transport-vehicle-act/art-76-7) - [Banking Act (銀行法)](https://japanlaw.org/en/banking-act): 2 provisions, among them [Article 2](https://japanlaw.org/en/banking-act/art-2), [Article 36](https://japanlaw.org/en/banking-act/art-36) ## Related - [Lease (賃貸借, ちんたいしゃく)](https://japanlaw.org/en/concepts/lease) - [Registration (登記, とうき)](https://japanlaw.org/en/concepts/registration) - [Rescission (取消し, とりけし)](https://japanlaw.org/en/concepts/rescission) - [Manifestation of intention (意思表示, いしひょうじ)](https://japanlaw.org/en/concepts/manifestation-of-intention) - [Right of lease (賃借権, ちんしゃくけん)](https://japanlaw.org/en/concepts/right-of-lease) --- ## Sources - Explanation: Written for this site with AI (claude-opus-5-5, 2026-09-23) - Where it is used, and how often: Worked out by this site from e-Gov's text - English names of the laws: Japanese Law Translation, Ministry of Justice (15 records)