Who has been buying System D Inc. stock?

8 distinct investors have filed 25 disclosed large-shareholding filings in System D Inc. (3804), most recently on 2025-10-29. 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 System D Inc. have?

System D Inc. has 25 buy-side and 5 sell-side disclosures on record, covering ¥692M ($4.5M) in total reported value, spanning 2021-05-18 to 2025-10-29.

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.

System D Inc. 3804

Company

株式会社システムディSystem D Inc.

Investors

Buys

Total Value

¥692M ($4.5M)

Avg Return

+23.35%

Last Filing

2025-10-29

System D Inc. (3804) has 25 disclosed large-shareholding filings and 5 disclosed disposals on record, filed by 8 distinct investors. Together those filings cover ¥692M ($4.5M) in reported transaction value. The earliest filing StockDrifts holds for System D Inc. is dated 2021-05-18; the most recent is 2025-10-29. Across these filings the average return since disclosure is +23.35%, 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
2025-10-29	BUY	Market Buy	ミリ・キャピタル・マネジメント・エルエルシー (MIRI Capital Management LLC) MIRI Capital Management LLC	activist	1.5M	¥2,135	-79.0%	¥142M ($913K)
2025-10-21	BUY	negotiated	堂山遼 douyama ryo	activist	277.6K	¥2,005	-77.7%	¥146M ($941K)
2025-10-21	SELL	negotiated	堂山達子 Tatsuko Doyama	strategic	305.8K	¥2,005	+77.7%	¥147M ($950K)
2025-10-21	BUY	negotiated	株式会社トライ Try Co., Ltd.	strategic	900.0K	¥2,005	-	-
2025-04-10	BUY	Market Buy	ミリ・キャピタル・マネジメント・エルエルシー (MIRI Capital Management LLC) MIRI Capital Management LLC	activist	1.4M	¥1,610	-72.2%	¥106M ($682K)
2025-01-14	BUY	Market Buy	ミリ・キャピタル・マネジメント・エルエルシー (MIRI Capital Management LLC) MIRI Capital Management LLC	activist	1.4M	¥1,429	-68.7%	¥94M ($605K)
2024-09-11	BUY	Market Buy	ミリ・キャピタル・マネジメント・エルエルシー (MIRI Capital Management LLC) MIRI Capital Management LLC	activist	1.3M	¥1,470	-69.5%	¥96M ($622K)
2024-08-19	BUY	Market Buy	ミリ・キャピタル・マネジメント・エルエルシー (MIRI Capital Management LLC) MIRI Capital Management LLC	activist	1.3M	¥1,444	-69.0%	¥109M ($702K)
2024-06-27	BUY	Market Buy	ミリ・キャピタル・マネジメント・エルエルシー (MIRI Capital Management LLC) MIRI Capital Management LLC	activist	1.2M	¥1,435	-68.8%	¥135M ($872K)
2024-05-28	BUY	Market Buy	ミリ・キャピタル・マネジメント・エルエルシー (MIRI Capital Management LLC) MIRI Capital Management LLC	activist	1.1M	¥1,180	-62.0%	¥78M ($505K)
2023-10-03	BUY	Market Buy	ミリ・キャピタル・マネジメント・エルエルシー (MIRI Capital Management LLC) MIRI Capital Management LLC	activist	1.0M	¥1,430	-68.7%	¥104M ($671K)
2023-01-23	BUY	Market Buy	ミリ・キャピタル・マネジメント・エルエルシー (MIRI Capital Management LLC) MIRI Capital Management LLC	activist	943.0K	¥1,361	-67.1%	¥89M ($576K)
2022-12-23	BUY	Market Buy	ミリ・キャピタル・マネジメント・エルエルシー (MIRI Capital Management LLC) MIRI Capital Management LLC	activist	877.5K	¥1,357	-67.0%	¥88M ($569K)
2022-11-25	BUY	Market Buy	ミリ・キャピタル・マネジメント・エルエルシー (MIRI Capital Management LLC) MIRI Capital Management LLC	activist	812.5K	¥1,395	-67.9%	¥95M ($614K)
2022-11-01	BUY	Market Buy	ミリ・キャピタル・マネジメント・エルエルシー (MIRI Capital Management LLC) MIRI Capital Management LLC	activist	743.7K	¥1,480	-69.7%	¥99M ($639K)
2022-10-13	BUY	Market Buy	ミリ・キャピタル・マネジメント・エルエルシー (MIRI Capital Management LLC) MIRI Capital Management LLC	activist	677.3K	¥1,446	-69.0%	¥118M ($764K)
2022-09-07	BUY	Market Buy	ミリ・キャピタル・マネジメント・エルエルシー (MIRI Capital Management LLC) MIRI Capital Management LLC	activist	595.1K	¥1,458	-69.3%	¥99M ($642K)
2022-08-05	BUY	Market Buy	ミリ・キャピタル・マネジメント・エルエルシー (MIRI Capital Management LLC) MIRI Capital Management LLC	activist	527.2K	¥1,369	-67.3%	¥90M ($580K)
2022-07-21	BUY	Market Buy	ミリ・キャピタル・マネジメント・エルエルシー (MIRI Capital Management LLC) MIRI Capital Management LLC	activist	461.3K	¥1,217	-63.2%	¥79M ($510K)
2022-06-29	BUY	Market Buy	ミリ・キャピタル・マネジメント・エルエルシー (MIRI Capital Management LLC) MIRI Capital Management LLC	activist	396.3K	¥1,231	-63.6%	¥83M ($537K)
2022-05-24	BUY	unknown	ミリ・キャピタル・マネジメント・エルエルシー (MIRI Capital Management LLC) MIRI Capital Management LLC	activist	328.6K	¥1,358	-67.0%	¥446M ($2.9M)
2022-05-12	BUY	Market Buy	堂山遼 douyama ryo	activist	204.4K	¥1,196	-62.5%	¥23M ($145K)
2022-05-12	SELL	Market Buy	堂山達子 Tatsuko Doyama	strategic	379.7K	¥1,196	+62.5%	¥30M ($196K)
2022-05-12	BUY	Market Buy	株式会社トライ Try Co., Ltd.	strategic	900.0K	¥1,196	-	-
2021-12-15	BUY	Market Buy	重田光時 Mitsutoki Shigeta	passive	367.0K	¥1,233	-63.7%	¥13M ($83K)
2021-10-26	BUY	Market Buy	ブイアイエス・アドバイザーズ・エルピー(VIS Advisors,LP)General Partner 泉智之 VIS Advisors,LP	passive	705.5K	¥1,346	-66.7%	¥94M ($604K)
2021-10-22	SELL	unknown	堂山道生(相続人代表堂山遼) Michio Doyama (Ryo Doyama, heir representative)	other	0	¥1,346	+66.7%	¥607M ($3.9M)
2021-10-22	BUY	unknown	堂山達子 Tatsuko Doyama	strategic	404.7K	¥1,346	-66.7%	¥276M ($1.8M)
2021-10-22	BUY	unknown	株式会社トライ Try Co., Ltd.	strategic	900.0K	¥1,346	-	-
2021-10-22	BUY	unknown	堂山遼 douyama ryo	activist	185.9K	¥1,346	-	¥250M ($1.6M)
2021-09-17	BUY	Market Buy	ブイアイエス・アドバイザーズ・エルピー(VIS Advisors,LP)General Partner 泉智之 VIS Advisors,LP	passive	636.3K	¥1,373	-67.4%	¥114M ($737K)
2021-07-14	SELL	Market Buy	サマランユーシッツ(SAMARANG UCITS) SAMARANG UCITS	passive	349.2K	¥1,534	+70.8%	¥103M ($662K)
2021-06-11	SELL	Market Buy	サマランユーシッツ(SAMARANG UCITS) SAMARANG UCITS	passive	415.7K	¥1,480	+69.7%	¥103M ($664K)
2021-05-18	BUY	Market Buy	ブイアイエス・アドバイザーズ・エルピー(VIS Advisors,LP)General Partner 泉智之 VIS Advisors,LP	passive	553.3K	¥1,479	-69.7%	¥105M ($676K)

Frequently asked questions

Who has been buying System D Inc. stock?: 8 distinct investors have filed 25 disclosed large-shareholding filings in System D Inc. (3804), most recently on 2025-10-29. 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 System D Inc. have?: System D Inc. has 25 buy-side and 5 sell-side disclosures on record, covering ¥692M ($4.5M) in total reported value, spanning 2021-05-18 to 2025-10-29.
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.

More on this data

Every trade listed above comes from an official regulatory disclosure. For how StockDrifts scores these disclosures, see the Japan insider signal tier research, or browse every Japanese stock we track.