The Japanese economy is significantly more consolidated than Germany's.

Vertical and Horizontal Integration (like what the 3 groups above do) is heavily regulated and litigated against in the EU [0][1], especially under Vestager.

Japan on the other hand doesn't actually regulate against either forms of market dominance. All three of those groups (called zaibatsu/keiretsu) have had market dominance in Japan since the 16th century.

That's why I recommended reading that book above - Antitrust in the Western sense doesn't actually exist in Asian countries, all of whom modeled their economies on Japan and with Japanese advice (METI) and aid (eg. ADB).

[0] - https://competition-policy.ec.europa.eu/antitrust-and-cartel...

[1] - https://www.cliffordchance.com/content/dam/cliffordchance/br...

Ah you meant the entire economy, not just the railways