"Twin sisters in Japan have become multi-millionaires after ..." reads to me like they suddenly became wealthy.
But in reality, they likely went from "millionaires" to "multi-millionaires". At least, it looks like their revenue (and thus estimated company value) grew linearly in recent years:
But in reality, they likely went from "millionaires" to "multi-millionaires". At least, it looks like their revenue (and thus estimated company value) grew linearly in recent years:
https://ipoget.com/ipo-colyinc/