No registration is required to seek remedies for infringement.
Monetary damages can be compensated. There are certain statutory presumptions to calculate damages but punitive damages are not available under Japanese law.
Injunctive relief, including seeking/preventing importation of infringing goods, is available as a remedy.
For moral rights, measures to correct and restore the honor and reputation of the author or performer are available (eg, publishing an apology in a newspaper).
Each joint owner can seek a remedy without the other owner's consent.
Criminal penalties are possible for infringement of copyright.