Conyac lets you hire freelancers worldwide for a wide range of tasks including programming, writing, design, and translation. The site is fully localized into Japanese, and most clients are currently Japanese, so gives freelancers access to Japanese clients.
Conyac version 1.0 debuted as a translation crowdsourcing service in 2009. Since then, it's evolved considerably. This month (around mid-July 2019), they are releasing version 2.0, which will expand their marketplace to cover a wide range of work that can be performed remotely by freelancers.
Disclosure: I'm an external contractor hired to do their English marketing/communications and help with English localization.
