Who has been buying Mitani Sangyo Co., Ltd. stock?

6 distinct investors have filed 14 disclosed large-shareholding filings in Mitani Sangyo Co., Ltd. (8285), most recently on 2026-05-08. Each filer, their role, the number of shares and the price at filing are listed in the table on this page.

How many insider filings does Mitani Sangyo Co., Ltd. have?

Mitani Sangyo Co., Ltd. has 14 buy-side and 7 sell-side disclosures on record, covering ¥9.4B ($60.8M) in total reported value, spanning 2021-05-12 to 2026-05-08.

Where does StockDrifts get Mitani Sangyo Co., Ltd. insider data?

From EDINET large-shareholding (5%+) reports — the official filing system run by the Financial Services Agency (Japan). StockDrifts parses each disclosure and matches it to daily price history; the original filings remain available directly from EDINET.

Do insider buys in Japanese stocks predict returns?

Not uniformly. StockDrifts scored 101,000+ Japanese large-shareholding filings on fixed 12-month forward returns and found the predictive power concentrated in specific filer types and filing patterns rather than spread evenly across all disclosures.

Mitani Sangyo Co., Ltd. 8285

Company

三谷産業株式会社Mitani Sangyo Co., Ltd.

Investors

Buys

Total Value

¥9.4B ($60.8M)

Avg Return

+91.81%

Last Filing

2026-05-08

Mitani Sangyo Co., Ltd. (8285) has 14 disclosed large-shareholding filings and 7 disclosed disposals on record, filed by 6 distinct investors. Together those filings cover ¥9.4B ($60.8M) in reported transaction value. The earliest filing StockDrifts holds for Mitani Sangyo Co., Ltd. is dated 2021-05-12; the most recent is 2026-05-08. All of it is parsed from EDINET large-shareholding (5%+) reports, the official disclosure system operated by the Financial Services Agency (Japan). Across these filings the average return since disclosure is +91.81%, measured from each filing date to the latest available close.

Price & insider activity (12 months)

Recent filings

Date	Type	Source	Insider	Purpose	Shares	Price at filing	Return	Value
2026-05-08	BUY	unknown	株式会社アルテミス	other	666.4K	¥681	-6.5%	¥454M ($2.9M)
2026-05-08	BUY	Market Buy	株式会社三谷サービスエンジン	strategic	2.1M	¥681	-6.5%	¥13M ($81K)
2026-05-08	BUY	unknown	株式会社アテナ	other	2.2M	¥681	-6.5%	¥1.5B ($9.5M)
2026-05-08	BUY	Market Buy	三谷株式会社	other	15.7M	¥681	-6.5%	¥6.6B ($42.8M)
2026-05-08	SELL	unknown	三谷充	other	61	¥681	+6.5%	¥6.6B ($42.8M)
2026-05-08	BUY	Market Buy	株式会社三谷サービスエンジン	strategic	2.1M	¥681	-6.5%	¥13M ($81K)
2026-05-08	BUY	unknown	株式会社アテナ	other	2.2M	¥681	-6.5%	¥1.5B ($9.5M)
2026-05-08	BUY	Market Buy	三谷株式会社	other	15.7M	¥681	-6.5%	¥6.6B ($42.8M)
2026-05-08	SELL	unknown	三谷充	other	61	¥681	+6.5%	¥6.6B ($42.8M)
2026-05-08	BUY	unknown	株式会社アルテミス	other	666.4K	¥681	-6.5%	¥454M ($2.9M)
2025-06-05	BUY	Market Buy	三谷充 mitani mituru	other	9.7M	¥337	+134.1%	¥2M ($13K)
2025-06-05	BUY	Market Buy	株式会社アルテミス Artemis Co., Ltd.	other	666.4K	¥337	+134.1%	¥225M ($1.4M)
2025-06-05	BUY	Market Buy	株式会社三谷サービスエンジン Mitani Service Engine Co., Ltd.	strategic	2.1M	¥337	+134.1%	¥2M ($13K)
2025-06-05	BUY	Market Buy	株式会社アテナ Athena Co., Ltd.	other	2.2M	¥337	+134.1%	¥730M ($4.7M)
2025-06-05	BUY	Market Buy	三谷株式会社 Mitani Co., Ltd.	other	6.0M	¥337	+134.1%	¥2.0B ($13.0M)
2025-04-28	BUY	unknown	株式会社三栄社 Saneisha Co., Ltd.	other	666.4K	¥346	+128.0%	¥231M ($1.5M)
2025-04-28	BUY	unknown	株式会社三谷サービスエンジン Mitani Service Engine Co., Ltd.	strategic	2.1M	¥346	+128.0%	¥723M ($4.7M)
2025-04-28	BUY	unknown	株式会社アテナ Athena Co., Ltd.	other	2.2M	¥346	+128.0%	¥749M ($4.8M)
2025-04-28	BUY	unknown	三谷株式会社 Mitani Co., Ltd.	other	6.0M	¥346	+128.0%	¥2.1B ($13.3M)
2025-04-28	BUY	Market Buy	株式会社三栄社 Saneisha Co., Ltd.	other	666.4K	¥346	+128.0%	¥231M ($1.5M)
2025-04-28	BUY	Market Buy	株式会社三谷サービスエンジン Mitani Service Engine Co., Ltd.	strategic	2.1M	¥346	+128.0%	¥723M ($4.7M)
2025-04-28	BUY	Market Buy	三谷株式会社 Mitani Co., Ltd.	other	6.0M	¥346	+128.0%	¥2.1B ($13.3M)
2025-04-28	BUY	Market Buy	三谷充 mitani mituru	other	9.7M	¥346	+128.0%	¥3.4B ($21.7M)
2025-04-28	BUY	unknown	三谷充 mitani mituru	other	9.7M	¥346	+128.0%	¥3.4B ($21.7M)
2025-04-28	BUY	Market Buy	株式会社アテナ Athena Co., Ltd.	other	2.2M	¥346	+128.0%	¥749M ($4.8M)
2025-04-04	BUY	Market Buy	三谷充 mitani mituru	other	9.7M	¥309	+155.3%	¥6M ($37K)
2025-04-04	BUY	Market Buy	株式会社三栄社 Saneisha Co., Ltd.	other	666.4K	¥309	+155.3%	¥206M ($1.3M)
2025-04-04	BUY	Market Buy	三谷株式会社 Mitani Co., Ltd.	other	6.0M	¥309	+155.3%	¥1.8B ($11.9M)
2025-04-04	BUY	Market Buy	株式会社三谷サービスエンジン Mitani Service Engine Co., Ltd.	strategic	2.1M	¥309	+155.3%	¥17M ($111K)
2025-04-04	BUY	Market Buy	株式会社アテナ Athena Co., Ltd.	other	2.2M	¥309	+155.3%	¥669M ($4.3M)
2023-09-19	BUY	unknown	株式会社三栄社 Saneisha Co., Ltd.	other	666.4K	¥339	+132.7%	¥226M ($1.5M)
2023-09-19	BUY	unknown	株式会社三谷サービスエンジン Mitani Service Engine Co., Ltd.	strategic	2.0M	¥339	+132.7%	¥8M ($54K)
2023-09-19	BUY	unknown	有限会社北都代行社 Hokuto Agent Co., Ltd.	other	2.2M	¥339	+132.7%	¥734M ($4.7M)
2023-09-19	BUY	unknown	三谷株式会社 Mitani Co., Ltd.	other	6.0M	¥339	+132.7%	¥2.0B ($13.1M)
2023-09-19	SELL	unknown	三谷充 mitani mituru	other	9.7M	¥339	-132.7%	¥670M ($4.3M)
2021-12-22	BUY	Market Buy	株式会社三栄社 Saneisha Co., Ltd.	other	666.4K	¥306	+157.8%	¥204M ($1.3M)
2021-12-22	BUY	Market Buy	株式会社三谷サービスエンジン Mitani Service Engine Co., Ltd.	strategic	2.0M	¥306	+157.8%	¥614M ($4.0M)
2021-12-22	BUY	Market Buy	有限会社北都代行社 Hokuto Agent Co., Ltd.	other	2.2M	¥306	+157.8%	¥663M ($4.3M)
2021-12-22	BUY	Market Buy	三谷株式会社 Mitani Co., Ltd.	other	6.0M	¥306	+157.8%	¥1.8B ($11.8M)
2021-12-22	BUY	Market Buy	三谷充 mitani mituru	other	11.7M	¥306	+157.8%	¥2M ($12K)
2021-07-20	BUY	unknown	公益財団法人三谷研究開発支援財団 The Mitani Foundation for Research and Development	other	4.0M	¥376	+109.8%	¥1.5B ($9.7M)
2021-05-25	BUY	Market Buy	株式会社三栄社 Saneisha Co., Ltd.	other	666.4K	¥401	+96.8%	¥268M ($1.7M)
2021-05-25	SELL	Market Buy	株式会社三谷サービスエンジン Mitani Service Engine Co., Ltd.	strategic	2.0M	¥401	-96.8%	¥7M ($48K)
2021-05-25	SELL	Market Buy	有限会社北都代行社 Hokuto Agent Co., Ltd.	other	2.2M	¥401	-96.8%	¥7M ($48K)
2021-05-25	SELL	Market Buy	三谷株式会社 Mitani Co., Ltd.	other	6.0M	¥401	-96.8%	¥25M ($160K)
2021-05-25	BUY	Market Buy	三谷充 mitani mituru	other	11.7M	¥401	+96.8%	¥168M ($1.1M)
2021-05-12	SELL	unknown	株式会社三栄社 Saneisha Co., Ltd.	other	666.4K	¥399	-97.7%	¥32M ($207K)
2021-05-12	BUY	unknown	三谷美智子 Michiko Mitani	other	2.5M	¥399	+97.7%	¥989M ($6.4M)

Frequently asked questions

Who has been buying Mitani Sangyo Co., Ltd. stock?: 6 distinct investors have filed 14 disclosed large-shareholding filings in Mitani Sangyo Co., Ltd. (8285), most recently on 2026-05-08. Each filer, their role, the number of shares and the price at filing are listed in the table on this page.
How many insider filings does Mitani Sangyo Co., Ltd. have?: Mitani Sangyo Co., Ltd. has 14 buy-side and 7 sell-side disclosures on record, covering ¥9.4B ($60.8M) in total reported value, spanning 2021-05-12 to 2026-05-08.
Where does StockDrifts get Mitani Sangyo Co., Ltd. insider data?: From EDINET large-shareholding (5%+) reports — the official filing system run by the Financial Services Agency (Japan). StockDrifts parses each disclosure and matches it to daily price history; the original filings remain available directly from EDINET.
Do insider buys in Japanese stocks predict returns?: Not uniformly. StockDrifts scored 101,000+ Japanese large-shareholding filings on fixed 12-month forward returns and found the predictive power concentrated in specific filer types and filing patterns rather than spread evenly across all disclosures.

Source filings

Every trade listed above is disclosed in EDINET large-shareholding (5%+) reports, filed with the Financial Services Agency (Japan). View the original EDINET filings for Mitani Sangyo Co., Ltd.. For how StockDrifts scores these disclosures, see the Japan insider signal tier research, or browse every Japanese stock we track.