Custody Bank of Japan operating model

Wiki route

This entry sits under banking index. Read it with the entity anchor Custody Bank of Japan (CBJ), the operating peer Master Trust Bank operating model and entity MTBJ, the landscape summary Japan master trust and custody bank landscape, the cross-camp matrix Japan trust bank vs global custodian comparison matrix, and the operating comparison trust-bank custody operating comparison. Pair it with JASDEC and JSCC for the settlement-infrastructure side, with Japan banking license tier comparison matrix for the regulatory tier, with the shareholder-side trust-bank pages SMTB and Mizuho Trust, and with Japan listed financial groups investable universe for the institutional context.

TL;DR

The Custody Bank of Japan (CBJ — 日本カストディ銀行) is the other half of Japan’s two-strong asset-administration utility, formed by the 2020-07-27 merger of JTSB (日本トラスティ・サービス信託銀行) and TCSB (資産管理サービス信託銀行). Its shareholder camp is the Sumitomo Mitsui Trust Group (33.3%) + Mizuho FG (27.0%) + Resona Bank (16.7%) + Dai-ichi Life (8.0%) + life-insurer (Asahi / Meiji Yasuda / Japan Post Insurance / Fukoku) axis — distinct from MTBJ’s MUFG Trust + Nippon Life + Meiji Yasuda + Norinchukin camp. Operationally CBJ does the same work as MTBJ: pension trust administration, securities-investment-trust administration, and securities custody — under the dual 銀行法 + 信託業法 license route, with direct JASDEC + BoJ JGB settlement participation. Its 「日本カストディ銀行（信託口）」 nominee name appears at the top of every TOPIX issuer’s shareholder register alongside MTBJ’s. The 2020 merger consolidated two duplicate systems into one mandate base and was driven by the same passive-fund growth and pension-asset scale that produced MTBJ. CBJ + MTBJ together account for the majority of Japan’s institutional custody volume.

1. Institutional position

Shareholder structure (public disclosure, as of 2020-07-27)

Why two specialist custodians, not one

The 2020-07 merger consolidated JTSB and TCSB but stopped short of merging with MTBJ. The public reading is:

1. Shareholder politics — the MUFG / 生保 axis vs the SMTB / Mizuho / Resona / 生保 axis would not consolidate easily without ceding control;
2. Risk concentration — Japan’s institutional asset-administration cannot rely on a single utility (operational risk + counterparty risk + 議決権 集中);
3. Cost arbitrage — duplicate systems within each camp (JTSB vs TCSB inside the SMTB / Mizuho camp) were redundant, but inter-camp duplication produces a competitive check.

The 2020 merger achieved the intra-camp consolidation. Inter-camp consolidation (CBJ + MTBJ) remains an open question.

Lineage diagram

SMTB / 第一生命 lineage
  日本トラスティ・サービス信託銀行 (JTSB) — 2000 設立
    ├── 旧中央三井信託 → SMTB
    ├── 旧住友信託 → SMTB
    └── 第一生命

Mizuho / Resona / 生保 lineage
  資産管理サービス信託銀行 (TCSB) — 2004 設立
    ├── みずほ信託 (Mizuho Trust)
    ├── りそな銀行 (旧 大和 / あさひ信託 系統)
    ├── Asahi Life, Meiji Yasuda, Japan Post Insurance, Fukoku Life
    └── 旧第一勧業富士 / 安田信託 系統

  ↓ 2020-07-27 merger

  日本カストディ銀行 (CBJ) — 株主 (2020-07-27 現在)
    ├── 三井住友トラストグループ (SMTH) 33.3%
    ├── みずほ FG (Mizuho FG) 27.0%
    ├── りそな銀行 (Resona) 16.7%
    ├── 第一生命 8.0%
    └── 朝日生命 5.0% / 明治安田 4.5% / かんぽ生命 3.5% / 富国生命 2.0%

Business-line map

Operating-function breakdown

The 「信託口」 nominee surface — CBJ specific

CBJ’s nominee name 「日本カストディ銀行（信託口）」 appears in the top-shareholder rows of substantially every TOPIX-100 issuer, often as 2nd or 3rd after MTBJ’s 「信託口」. The pattern is:

vs MTBJ — operating-detail comparison

vs full-service trust banks

CBJ does the processing while its trust-bank shareholders do the client relationship + front-office mandate. This vertical split is intentional and is the reason the trust-bank shareholders have not absorbed CBJ back into their consolidated operations.

vs global custodians

4. Fees and revenue structure

CBJ does not publicly disclose detailed fee schedules. The public-domain reading is:

Why CBJ fee economics resemble MTBJ closely

Both run the same product set against similar mandate scales. Their fee pricing is anchored by:

2. GPIF tender pressure — GPIF runs periodic 資産管理機関 panels where CBJ and MTBJ both compete; both incumbent-priced and challenger-priced.
3. Passive-fund AUM growth — passive index funds have driven up CBJ-administered AUC while pushing down per-bp fees, producing volume-up / margin-down dynamics.

Cross-bank fee-economy reading

For granular MTBJ + CBJ + megabank trust-arm + global-custodian fee comparison see trust bank fee structure comparison.

Regulatory stack

Accounting treatment

Merger-accounting note

The 2020-07-27 JTSB + TCSB merger involved system integration over multiple years; integration costs flowed through CBJ P&L and were absorbed by shareholder parents in their consolidated trust-bank operating segments. The granular cost recovery and IT-write-down profile is not publicly disclosed (CBJ is non-listed and reports only summary figures; merger goodwill specifics sit in shareholder-parent consolidated disclosure).

6. JASDEC / clearing infrastructure connection

┌─────────────────────────────────────────────────────────────────┐
│ Beneficial owners (GPIF / corporate pensions / 投信 / insurers)  │
└─────────────────────────────┬───────────────────────────────────┘
                              │  mandate
                              ▼
┌─────────────────────────────────────────────────────────────────┐
│ Asset managers (front-office discretion + voting opinion)        │
│ — SMTB AM affiliates, Mizuho AM, Resona AM, etc.                 │
└─────────────────────────────┬───────────────────────────────────┘
                              │  instruction
                              ▼
┌─────────────────────────────────────────────────────────────────┐
│ Custody Bank of Japan (trust account / nominee)                  │
│ — recordkeeping, NAV, CA processing, voting admin                │
└─┬────────────┬────────────┬───────────────┬────────────────────┬─┘
  │            │            │               │                    │
  ▼            ▼            ▼               ▼                    ▼
┌───────────┐┌─────────────┐┌──────────────┐┌──────────────────┐┌─────────────────┐
│ JASDEC    ││ JSCC        ││ BoJ JGB      ││ Global custodians│ │ ICJ voting plat.│
│ (equities,││ (CCP for    ││ book-entry   ││ for foreign sub- │ │ (electronic     │
│ 社債, CP, ││ cash equity)││ (JGB         ││ custody          │ │ proxy voting)   │
│ 投信)     ││             ││ settlement)  ││                  │ │                 │
└───────────┘└─────────────┘└──────────────┘└──────────────────┘└─────────────────┘

Direct JASDEC participation

CBJ is a direct participant in:

• 株式振替制度 (dematerialized listed shares)
• 一般債振替制度 (corporate bonds: 普通社債, 転換社債)
• 短期社債振替制度 (CP)
• 投資信託振替制度 (publicly offered 投信 units)

JSCC + DVP

CBJ’s cash-equity settlement runs through JSCC as the central counterparty, producing DVP-X1 / X2 / X3 quality settlement. JSCC also runs CCP services for repos and OTC derivatives — CBJ’s exposure to these layers depends on individual client mandate scope.

BoJ JGB book-entry

CBJ holds a direct account in the BoJ JGB book-entry system, supporting DVP JGB settlement for pension and 投信 mandates without intermediate sub-custody.

Foreign-asset sub-custody chain

For non-JP assets in CBJ-administered mandates:

CBJ (record-name trust-account)
  → Global custodian (BNY / State Street / JPM / Citi)
    → Local sub-custodian in foreign market
      → Local CSD

Related

• INDEX
• japan-master-trust-and-custody-bank-landscape
• japan-trust-bank-custody-map
• japan-trust-bank-vs-global-custodian-comparison-matrix
• trust-bank-custody-operating-comparison
• master-trust-bank-operating-model
• jasdec-settlement-operations
• trust-bank-fee-structure-comparison
• pension-trust-mandate-allocation-japan
• japan-banking-license-tier-comparison-matrix
• custody-bank
• master-trust-bank
• sumitomo-mitsui-trust
• mizuho-trust-bank
• mitsubishi-ufj-trust-bank
• dai-ichi-life
• bny-mellon-japan
• state-street-japan
• jpmorgan-japan
• citigroup-japan
• japan-securities-depository-center
• japan-securities-clearing-corp
• japan-market-infrastructure-map
• japan-listed-financial-groups-investable-universe

Sources

• Custody Bank of Japan: official site, about us, business explanation, corporate information page, English corporate page.
• 三井住友信託銀行「スケールメリットの追求」資産管理業務ページ（CBJ AUC: 総預かり資産 約696兆円 / 信託財産 476兆円、2025-03-31）— https://www.smtb.jp/business/instrument/management/scale
• 日本マスタートラスト信託銀行 2024 年度決算（MTBJ 管理資産残高 約770兆円、2025-03-31）— https://www.mastertrust.co.jp/assets/pdf/financial/zm20250521.pdf
• Trust Companies Association of Japan: trust-assets-under-management statistics.
• FSA: trust-business financial institution list, bank license list.
• JASDEC: securities book-entry and depository system materials.
• JSCC: clearing and DVP cash-equity materials.
• BoJ: JGB book-entry settlement system materials.
• Wikipedia (cross-reference): 株式会社日本カストディ銀行, JTSB, TCSB historical entries. — CBJ 株主構成（2020-07-27 現在）：三井住友トラストグループ 33.3% / みずほ FG 27.0% / りそな銀行 16.7% / 第一生命 8.0% / 朝日生命 5.0% / 明治安田生命 4.5% / かんぽ生命 3.5% / 富国生命 2.0%。https://ja.wikipedia.org/wiki/日本カストディ銀行 （2026-05-30 確認。旧版の「SMTB ~46.5% / Mizuho ~27% / Daiwa-affiliated」の出資者表記を訂正。46.5% は日本マスタートラスト信託における MUFG 信託の比率の誤転記、Daiwa Securities は CBJ の株主ではなく正しくは りそな銀行 16.7%）