In Japan, the trademark law allows for registration of defensive marks under Article 64. The proprietor of a well-known registered trademark (original registration) which has been applied for in respect of certain goods/services can obtain defensive registration for the identical mark on goods/services unrelated to those designated under the original registration if he feels that there causes a likelihood of confusion when unauthorized entity uses the identical mark in respect of those goods/services.

Trademarks in Japan are declared well-known via judicial or administrative processes. Under the judicial process, the appeal/trial board or courts recognize trademarks as well-known in their decisions. Under the administrative process, the Japan Patent Office (JPO) recognizes a mark as well-known when the proprietor registers a mark as a defensive mark or proves substantial good will bestowed on the mark through cancellation, opposition, and invalidation procedures.

Further, JPO maintains a database of well-known trademarks, recognized either through judicial process or administrative process, which is accessible to the public at large.
If you are in need to search Japanese well-known trademarks, please access the following URL.
https://www2.j-platpat.inpit.go.jp/chomei/search_e.cgi?login&1503051142973

MASAKI MIKAMI, Attorney at IP Law
Founder of MARKS IP LAW FIRM