The biggest biotechnology company in Japan almost didn't get built.

When Patrick C. Reid, now managing director of PeptiDream Inc., arrived in Japan about a decade ago, he found investors reluctant to put much money into drug startups — even though the country had world-class universities and pharma companies. A string of biotech firms had seen their shares slump by the mid-2000s, leaving the sector with an unfavorable image.

So when PeptiDream was first set up, its co-founders had to dig deep into their own pockets to get it up and running. It took more than 10 years for investors to get over some of their previous disappointments with IPOs in the Japanese biotech industry. But there has since been a resurgence of interest in the sector — aided partly by a more nimble drug regulator and by share gains for newer companies.