Price-to-income ratio
The average price of a new 70 sqm apartment in 1990 in Tokyo was 107,660,000 Yen, or 1,538,000 Yen/sqm, while the average annual income was 5,940,000 Yen. Before the bubble, the average price-to-income ratio in 1985 was 8.08.
Financial Times article (https://www.ft.com/content/2ba1cb74-f598-3a4e-9edd-4e55a48d3480)
So in 1990, new home price is ~18x annual income and before bubble is ~8x.
Relative performance
Price rose ~4x in 15 years
Peak to bottom took 5 years; declined ~40% (1990-1995)
From 1975 – 1995, price still rose ~2.5x in 20 years.
Source: Home Ownership and Economic Change in Japan
Relative to global (before bubble)
Price-to-income ratio is actually more than doubling US-level and is the highest among developed countries.
Source: Introduction to “Housing Markets in the U.S. and Japan”
However, Japan’s women work participation rate is lower than the US back then, which can impact household income.
Source: Lessons from the rise of women’s labor force participation in Japan
Income level
Peak income is actually lower for later generations.
Source: The Impact of the Rise and Collapse of Japan’s Housing Price Bubble on Households’ Lifetime Utility
Due to other reasons, e.g. Asia Financial Crisis, the property market didn’t seem to recover until later years.
Source: New apartment prices in Japan since 1956,
Tokyo Kantei via JAPAN PROPERTY CENTRAL