[Filligree]

Copyright holders might not, but isn't one of the main distinctions between civil and criminal law that, in the latter case, the state can (and in theory is obliged to) prosecute criminal cases regardless of the copyright holder's thoughts?

[seishan]

In Japan, copyright law can't be enforced without the complaint of the rights holder.[1] If you have some spare time, I'd recommend reading the Copyright Law [2] for the powers that are legally provided to the rights holders and specifically, "Measures Against Infringement" [3]. They're quite fascinating.

Disclaimer: IANAL, much less a Japanese legal scholar.

[1] https://www.tofugu.com/japan/doujinshi-definition/ [2] http://www.japaneselawtranslation.go.jp/law/detail/?id=2506&... [3] http://www.cric.or.jp/english/csj/csj5.html