>>71683836By the contract, they more or less can hold you at least until it runs out, and even then, it auto-renews (and they can, for instance, amend it to extend while you're streaming, and you automatically accept). The financial penalties for ending the contract early are MASSIVE, especially if you're terminated in the process, and they can cost you your equipment to boot.
However, the contract is more or less unenforceable outside of Japan, and the penalties are technically illegal, even in Japan. But of course that all depends on the talent understanding that, and not simply believing Niji's threats. The contract isn't designed to be enforceable, it's designed to be terrifying.
And of course the talents can't say anything negative about Nijisanji while in Japan, or risk getting served to fight a three year prison sentence for defamation.
