The 2016 Mirai fuel cell vehicle will go into production later this month at the old LFA workshop, which is located behind Toyota's Motomachi assembly plant in Toyota City. The skilled workers there have been doing other things (like building bicycles) since the last LFA was finished and now Automotive News says they will hand-build the Mirai so that the car can get the attention to detail Toyota wants and because there won't be that many of the hydrogen cars made for a while.
The 200 Mirai orders are "mostly from government and corporate fleets." – Masamoto Maekawa
Toyota has already said it will sell only 3,000 Mirai FCVs in the US by the end of 2017 (it won't arrive here until late 2015, with deliveries in Japan starting earlier). With 200 orders already in and a plan to build only 700 in 2015, Toyota is already talking about delivery delays. Toyota's executive vice president for domestic sales, Masamoto Maekawa, said that, "the 200 orders are mostly from government and corporate fleets."
Production could remain at LFA Works for a while. One Toyota exec said that even if the company makes 2,000 Mirais a year, that would still be only 10 each day. Doesn't sound like there's going to be anyone working weekends for a while.