We first heard that Apple would be building a new R&D facility in Japan back in December. The Yokohama mayor Fumiko Hayashi announced in a press conference that Apple had purchased a space that once belonged to Panasonic for the construction of such a facility, according to Japanese news site NKH (translated from Japanese):

Apple plans to build a large technology development facility of approximately 25,000 square meters floor space, and will have already bought part of the Tsunashimahigashi Kohoku-ku, Yokohama Panasonic Factory site.

The building will reportedly be environmentally friendly, keeping energy usage to a minimum. Construction of the building will begin later this year, with goal of completing it at some point in 2016.

Source: NKH, Asahi Shimbun via: Macotakara