Japanese investment company Metaplanet has made another Bitcoin purchase, bringing its stash to nearly 640 Bitcoin and sending its stock surging over 10%. On Oct. 7, Metaplanet announced its latest Bitcoin purchase as the Tokyo-listed firm scooped up another 108.78 Bitcoin (BTC), worth roughly $6.92 million at its current price of around $63,600. Metaplanet, which has been dubbed “Asia’s MicroStrategy” after the American BTC buying firm, has been aggressively buying BTC and has amassed more than 215 BTC over the week following a 107.91 BTC purchase on Oct. 1. Its holdings now total 639.5 BTC w…