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Katsumasa Nakayama

Katsumasa Nakayama — Senior Yamaguchi-gumi underboss killed during the Yama-Ichi War.

Yamaguchi-gumiSenior yamaguchi gumi underboss killed during the yama ichi war.
Biography

Katsumasa Nakayama — Senior Yamaguchi-gumi underboss killed during the Yama-Ichi War.

Role and period

Senior Yamaguchi-gumi underboss killed during the Yama-Ichi War.

Primary organization/context: Yamaguchi-gumi. Period: 1980s.

Why this person matters

Assassinated alongside Masahisa Takenaka in 1985.

This profile is designed as a canonical node rather than a stand-alone celebrity biography. The priority is to show where this person sits in the hierarchy, who they succeeded or challenged, which organization they belonged to at different points in time, and which events changed their position.

Network position

The strongest existing the archive connections are Yamaguchi Gumi, Yama Ichi War, Assassination Of Masahisa Takenaka. Those links should be treated as dated relationships where affiliation or leadership changed over time.

Expansion path

A later deep audit should add: – verified birth/death dates where available; – exact leadership titles and dates; – convictions, sentences or major court outcomes where applicable; – major rivals, allies and succession relationships; – documented events that justify the person’s place in the Japan graph.

This profile should enrich the existing canonical profile rather than create parallel pages for the same individual.

Sources / audit anchors

– [Japan National Police Agency — Police of Japan / Organized Crime](https://www.npa.go.jp/english/) — Primary official background source for designated boryokudan, enforcement and organized-crime policy. – [Japan National Police Agency — White Papers](https://www.npa.go.jp/publications/whitepaper/) — Primary archive for historical and modern boryokudan data.

Timeline

Key events

1985-01-26

Assassination of Masahisa Takenaka

Gunmen attacked the newly installed Yamaguchi-gumi boss, killing him and two associates and accelerating an already dangerous syndicate split.

1985-01-27

Yama–Ichi War

A succession dispute inside Japan’s largest yakuza syndicate became a nationwide gang war after its new boss was assassinated.

Connections

People, groups and places

Organization

Yamaguchi-gumi

Related To [4][7]
Shop

Collectibles & memorabilia

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Sources

References

  1. [1]White Paper on Police 2025 — Organized Crime CountermeasuresTier 1
    National Police Agency of Japan
    Supports
    View source ↗
  2. [2]Japan National Police Agency — 1999 White PaperTier 2
    Supports
    View source ↗
  3. [3]Japan National Police Agency — 2017 White Paper, Measures against Organized CrimeTier 2
    Supports
    View source ↗
  4. [4]Japan National Police Agency — Police of Japan / Organized CrimeTier 2
    MentionsSupports
    View source ↗
  5. [5]Japan National Police Agency — White Paper 2009, designated boryokudan detailsTier 2
    Supports
    View source ↗
  6. [6]Japan National Police Agency — White Paper 2017Tier 2
    Supports
    View source ↗
  7. [7]Japan National Police Agency — White PapersTier 2
    MentionsSupports
    View source ↗
  8. [8]Hard-Up Yakuza Struggle to Earn a LivingTier 2
    Nippon.com
    Supports
    View source ↗
  9. [9]The Japanese Mafia: Yakuza, Law, and the StateTier 2
    Oxford University Press
    Supports
  10. [10]Yakuza: Japan's Criminal UnderworldTier 2
    University of California Press
    Supports
  11. [11]Japanese crime gangs spread to AmericaTier 2
    UPI
    Supports
    View source ↗
  12. [12]Riot police mobilized after Takenaka killingTier 2
    UPI
    Supports
    View source ↗