Iwao Aso麻生 巌

Director, Sumiseki Holdings, Inc.

Net worth (est.)
¥155B
#22 in Japan
Listed shares · incl. ¥155B via asset-management cos.
Executive pay
—
Not disclosed
Dividends (a year)
¥5.3B
#11
Own name ¥0 / via companies ¥5.3B
Total income (est.)
¥5.3B
#12
Pay + dividends, before tax
Other assets (est.)
¥13.7B
¥168B with shares
After-tax income 2023–2026 (incl. ¥416M from share sales), before spending
Inheritance tax (est.)
¥30.4B
#35
If a spouse and two children inherit in statutory shares (change)

Other assets (est.): the sum of each year's after-tax income (pay + dividends in own name − estimated taxes and social insurance) dividends retained by asset-management companies (less about 20% corporate tax), and proceeds from share sales (the drop in shares from the previous year × share price, less 20.315% tax, or about 30% for asset-management companies), for the years we have data. Spending, real estate, donations and savings from earlier years are not reflected.

Asset-management companies: Aso Co., Ltd.est., Aso Co., Ltd.est. (their holdings are included in net worth)

Holdings

CompanyHeld bySharesStakePriceValueDividends
Daiho Corporation
1822 · FY ending Mar 2026
Aso Co., Ltd. 44,530,000 50.12% ¥769 ¥34.3B ¥1.5B
Sumiseki Holdings, Inc.
1514 · FY ending Mar 2026
Aso Co., Ltd. 34,044,000 56.91% ¥992 ¥33.8B ¥681M
Wakachiku Construction Co.,Ltd.
1888 · FY ending Mar 2026
Aso Co., Ltd. 5,424,200 42.26% ¥4,087 ¥22.2B ¥732M
Tsuzuki Denki Co., Ltd.
8157 · FY ending Mar 2026
Aso Co., Ltd. 4,500,000 23.97% ¥3,453 ¥15.5B ¥567M
株式会社西日本フィナンシャルホールディングス
7189 · FY ending Mar 2026
Aso Co., Ltd. 3,064,000 2.19% ¥3,704 ¥11.3B ¥362M
Nittetsu Mining CO.,Ltd.
1515 · FY ending Mar 2026
Aso Co., Ltd. 3,937,000 5.00% ¥2,483 ¥9.8B ¥650M
Taiheiyo Cement Corporation
5233 · FY ending Mar 2026
Aso Co., Ltd. 2,623,000 2.35% ¥3,500 ¥9.2B ¥262M
KOSAIDO Holdings Co., Ltd.
7868 · FY ending Mar 2026
Aso Co., Ltd. 13,499,000 9.13% ¥487 ¥6.6B ¥180M
CHIKARANOMOTO HOLDINGS Co.,Ltd.
3561 · FY ending Mar 2026
Aso Co., Ltd. 2,950,000 9.75% ¥1,447 ¥4.3B ¥59.0M
アグロ カネショウ株式会社
4955 · FY ending Dec 2023
Aso Co., Ltd. 2,199,000 18.15% ¥1,537 ¥3.4B ¥70.4M
Hurxley Holdings Corporation
7561 · FY ending Mar 2026
Aso Co., Ltd. 1,920,000 10.38% ¥674 ¥1.3B ¥53.8M
YAMAX Corp.
5285 · FY ending Mar 2026
Aso Co., Ltd. 687,000 6.77% ¥1,538 ¥1.1B ¥45.3M
Kyowanissei Co.,Ltd.
1981 · FY ending Mar 2026
Aso Co., Ltd. 730,000 6.97% ¥1,383 ¥1.0B ¥36.5M
Nakabohtec Corrosion Protecting Co.,Ltd.
1787 · FY ending Mar 2026
Aso Co., Ltd. 153,000 6.26% ¥6,181 ¥946M ¥51.3M
Rkb Mainichi Holdings Corporation
9407 · FY ending Mar 2026
Aso Co., Ltd. 155,400 7.08% ¥5,899 ¥917M ¥11.7M
Yamau Holdings Co., Ltd.
5284 · FY ending Mar 2026
Aso Co., Ltd. 400,000 6.60% ¥2,127 ¥851M ¥44.0M
Isewan Terminal Service Co.,Ltd.
9359 · FY ending Mar 2026
Aso Co., Ltd. 800,000 3.13% ¥958 ¥767M ¥29.6M
AuBEX CORPORATION
3583 · FY ending Mar 2026
Aso Co., Ltd. 445,000 14.76% ¥1,338 ¥595M ¥15.6M
SE Corporation
3423 · FY ending Mar 2026
Aso Co., Ltd. 975,000 3.20% ¥272 ¥265M ¥12.7M
Daisan Co.,Ltd.
4750 · FY ending Apr 2026
Aso Co., Ltd. 114,000 1.78% ¥576 ¥65.7M ¥2.5M
Daiho Corporation
1822 · FY ending Mar 2026 · Director
Own name — — ¥769 ¥0 ¥0
Nittoc Construction Co.,Ltd.
1929 · FY ending Mar 2026 · Director
Own name — — ¥1,237 ¥0 ¥0
Sumiseki Holdings, Inc.
1514 · FY ending Mar 2026 · Director
Own name — — ¥992 ¥0 ¥0
麻生フオームクリート株式会社
1730 · FY ending Mar 2024
Aso Co., Ltd. 1,420,000 41.59% — — ¥4.3M

By year

YearNet worthPayDividendsTotal incomeTaxes (est.)After tax (est.)Share sales (after tax)
2026¥155B—¥5.3B¥5.3B¥0¥0¥353M
2025¥99.3B—¥4.6B¥4.6B¥0¥0—
2024¥96.9B—¥3.7B¥3.7B¥0¥0¥63.1M
2023¥72.7B—¥2.9B¥2.9B¥0¥0—

Grouped by the calendar year of each company's fiscal year-end. Years in which the person was not among the top 10 shareholders of a company exclude that company.

Inheritance tax (estimate)

Estate ¥111B = listed shares in own name ¥0 + shares held via asset-management companies ¥97.4B (value ¥155B less 37% corporate tax on unrealized gains) + other assets (est.) ¥13.7B

Total inheritance tax paid: ¥30.4B (27.4% of the estate).

HeirInheritsTaxAfter tax
Spouse¥55.6B¥0¥55.6B
Each child¥27.8B¥15.2B¥12.6B

Japanese inheritance tax, assuming the estate is split in statutory shares. A spouse pays no tax up to ¥160M or the statutory share, whichever is larger. Family size is not in the securities reports, so you can choose it (with no children, parents or siblings also become heirs, so the real figure differs). Business-succession deferrals, lifetime gifts, donations to foundations, debts and other reliefs are not reflected.

Estimates from annual securities reports (EDINET). The English name is romanized automatically and may differ from the spelling the person uses. Methodology · Corrections and removal requests: contact