The only “derivative liability” in Japan is contributory infringement. A main difference between the US and JP is that contributory infringement is independent from direct infringement in Japan.

To prove contributory infringement in Japan, a patent holder must prove one of (a), (b), or (c) below:

(a) 1. An infringer manufactures, sells, imports or offers for sale articles (the particular material) to be used for the manufacture of the patented product or the use of the patented process. Generally distributed articles in Japan are excluded;
2. The articles are indispensable for solving the problems through the patented product or the patented process concerned; and
3. The infringer knows of the patent and that the articles are to be used for the working of the patented product or the patented process.

(b) An infringer manufactures, sells, imports or offers for sale articles (the particular material) to be used exclusively for the manufacture of the patented product or the use of the patented process.

(c) An infringer holds a patented product (the particular material) or a product manufactured by a patented process for the purpose of sale or export. The act of holding the product for sale is not direct infringement in Japan.  However, holding the product prior to selling the product is considered to be indirect infringement.

Yes, the imported product can infringe the patented method.

Under Japanese patent law, the following is included in infringing acts:
“In the case of an invention of a process of manufacturing a product, acts of using, assigning, or importing, exporting or offering for assignment of the product manufactured by the process, in addition to the acts of using the process.”