Long content to slug it out in their fragmented, $70bn-a-year domestic market, Japanese drugmakers have been coming out lately. Dainippon Sumitomo Pharma’s $2.6bn acquisition of Boston-based Sepracor is the latest multibillion-dollar Japanese takeover of a foreign drugmaker. Japanese pharma has spent more than $20bn on foreign deals since last year, compared with just $5.3bn domestically.