Real interest rates in Japan were on par with in the US in the mid-2000s [0], and only entered the negative range when the US began dropping interest rates to near 0 during the GFC [0].
The bigger issue in was the hangover of the 1990s Japanese bust which lead to larger players tightening their belts at the expense of smaller players [1]
The big players in Japan are also similarly old (usually 300-500 year old guilds converted into corporations/zaibatsus in the 19th century)
There is also a succession crisis brewing in plenty of Japanese, Korean, and Taiwanese businesses. One person in my network is leaving American Tech PE/VC to concentrate on buying out Korean and a Japanese companies facing issues around succession now - just like American SMEs businesses faced in the 1970s-2000s.
Ik people like to shoehorn the Japanese experience to extrapolate American and Western policy, but the Japanese economy is structured very differently from Western economies with an entirely different view on antitrust (ambivalent to opposed), welfare (highly supportive), inflation (keep it as low as possible), and state intervention (highly supportive).
The only developed countries that can safely be compared to the Japanese economy are South Korea and Taiwan (maybe Dirigisme-era France and Italy pre-1990s, but they had the benefits of the EC/EU which made stuff significantly different).
I recommend reading "The Japanese Economy" by Takatoshi Ito and Takeo Hoshi [2] and "Corporate Financing and Governance in Japan" by Takeo Hoshi and Anil Kashyap [3]
[0] - https://data.worldbank.org/indicator/FR.INR.RINR?end=2013&lo...
[1] - https://www.japantimes.co.jp/news/2000/01/03/national/execs-...
[2] - https://mitpress.mit.edu/9780262538244/the-japanese-economy/
[3] - https://mitpress.mit.edu/9780262582483/corporate-financing-a...
