This incredible discovery has been made in the Japanese city of Chiba, just a short drive from Tokyo. Arcade Otaku forum poster keisuke999 recently uncovered the details of this amazing find, along with a detailed inventory of the building's contents in pictures.

Amongst the selection was just short of fifty Sega Aero and Astro City cabinets, along with a handful of Namco machines too. Within these cabinets were also original arcade game boards including the likes of Street Fighter 2 Champion Edition, Metal Slug X, Donkey Kong, Pengo, Magical Tetris Challenge, Galaxian, Raiden 2 and even Columns.
http://www.retrocollect.com/News/property-purchase-in-japan-uncovers-disused-classic-arcade.html
https://imgur.com/a/yqxip