Who has been buying Media Kobo, Inc. stock?

4 distinct investors have filed 3 disclosed large-shareholding filings in Media Kobo, Inc. (3815), most recently on 2026-04-16. 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 Media Kobo, Inc. have?

Media Kobo, Inc. has 3 buy-side and 11 sell-side disclosures on record, covering ¥1.3B ($8.6M) in total reported value, spanning 2021-08-27 to 2026-04-16.

Where does StockDrifts get Media Kobo, Inc. 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.

Media Kobo, Inc. 3815

Company

株式会社メディア工房Media Kobo, Inc.

Investors

Buys

Total Value

¥1.3B ($8.6M)

Avg Return

+2.50%

Last Filing

2026-04-16

Media Kobo, Inc. (3815) has 3 disclosed large-shareholding filings and 11 disclosed disposals on record, filed by 4 distinct investors. Together those filings cover ¥1.3B ($8.6M) in reported transaction value. The earliest filing StockDrifts holds for Media Kobo, Inc. is dated 2021-08-27; the most recent is 2026-04-16. 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 +2.50%, 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
2026-07-09	SELL	Market Buy	マイルストーン・キャピタル・マネジメント株式会社 Milestone Capital Management,Ltd.	passive	1.5M	¥443	-1.4%	¥27M ($174K)
2026-04-16	SELL	Market Buy	マイルストーン・キャピタル・マネジメント株式会社 Milestone Capital Management,Ltd.	passive	1.6M	¥447	+0.2%	¥54M ($345K)
2026-02-25	SELL	Market Buy	マイルストーン・キャピタル・マネジメント株式会社 Milestone Capital Management,Ltd.	passive	1.7M	¥490	+8.8%	¥57M ($368K)
2026-01-29	SELL	Market Buy	マイルストーン・キャピタル・マネジメント株式会社 Milestone Capital Management,Ltd.	passive	1.9M	¥513	+12.9%	¥59M ($381K)
2025-11-28	SELL	Market Buy	マイルストーン・キャピタル・マネジメント株式会社 Milestone Capital Management,Ltd.	passive	2.0M	¥520	+14.0%	¥60M ($387K)
2025-08-22	BUY	unknown	株式会社エヌカルテット N Quartet Co., Ltd.	unknown	4.9M	¥591	-24.4%	¥2.9B ($18.5M)
2025-08-22	SELL	unknown	長沢敦子 Atsuko Nagasawa	activist	182.6K	¥591	+24.4%	¥668K ($4K)
2025-08-22	SELL	unknown	長沢一男 Nagasawa Kazuo	activist	1.8M	¥591	+24.4%	¥9M ($60K)
2025-08-19	SELL	Market Buy	マイルストーン・キャピタル・マネジメント株式会社 Milestone Capital Management,Ltd.	passive	2.2M	¥601	+25.6%	¥31M ($202K)
2025-07-15	SELL	Market Buy	マイルストーン・キャピタル・マネジメント株式会社 Milestone Capital Management,Ltd.	passive	2.3M	¥591	+24.4%	¥11M ($73K)
2025-06-26	BUY	unknown	長沢敦子 Atsuko Nagasawa	unknown	184.2K	¥572	-21.9%	¥105M ($680K)
2025-06-26	BUY	unknown	株式会社エヌカルテット N Quartet Co., Ltd.	unknown	4.9M	¥572	-21.9%	¥2.8B ($17.9M)
2025-06-26	SELL	unknown	長沢一男 Nagasawa Kazuo	activist	1.9M	¥572	+21.9%	¥65M ($421K)
2025-06-13	BUY	Market Buy	マイルストーン・キャピタル・マネジメント株式会社 Milestone Capital Management,Ltd.	passive	2.3M	¥551	-18.9%	¥1.3B ($8.3M)
2024-08-26	BUY	Market Buy	株式会社エヌカルテット N Quartet Co., Ltd.	unknown	4.9M	¥538	-16.9%	¥2.6B ($16.9M)
2024-08-26	SELL	Market Buy	長沢敦子 Atsuko Nagasawa	activist	184.2K	¥538	+16.9%	¥2M ($12K)
2024-08-26	BUY	Market Buy	長沢一男 Nagasawa Kazuo	activist	2.0M	¥538	-16.9%	¥13M ($86K)
2022-09-01	BUY	unknown	長沢敦子 Atsuko Nagasawa	unknown	188.0K	¥399	+12.0%	¥75M ($484K)
2022-09-01	BUY	unknown	株式会社エヌカルテット N Quartet Co., Ltd.	activist	4.9M	¥399	+12.0%	¥1.9B ($12.5M)
2022-09-01	BUY	unknown	長沢一男 Nagasawa Kazuo	activist	2.0M	¥399	+12.0%	¥779M ($5.0M)
2022-08-29	BUY	unknown	長沢敦子 Atsuko Nagasawa	unknown	188.0K	¥478	-6.5%	¥90M ($580K)
2022-08-29	BUY	unknown	株式会社エヌカルテット N Quartet Co., Ltd.	unknown	4.9M	¥478	-6.5%	¥2.3B ($15.0M)
2022-08-29	SELL	unknown	長沢一男 Nagasawa Kazuo	activist	2.0M	¥478	+6.5%	¥32M ($209K)
2021-08-27	BUY	Market Buy	長沢敦子 Atsuko Nagasawa	unknown	188.0K	¥312	+43.3%	¥59M ($378K)
2021-08-27	BUY	Market Buy	株式会社エヌカルテット N Quartet Co., Ltd.	unknown	4.9M	¥312	+43.3%	¥1.5B ($9.8M)
2021-08-27	BUY	Market Buy	長沢一男 Nagasawa Kazuo	activist	2.0M	¥312	+43.3%	¥44M ($282K)

Frequently asked questions

Who has been buying Media Kobo, Inc. stock?: 4 distinct investors have filed 3 disclosed large-shareholding filings in Media Kobo, Inc. (3815), most recently on 2026-04-16. 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 Media Kobo, Inc. have?: Media Kobo, Inc. has 3 buy-side and 11 sell-side disclosures on record, covering ¥1.3B ($8.6M) in total reported value, spanning 2021-08-27 to 2026-04-16.
Where does StockDrifts get Media Kobo, Inc. 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 Media Kobo, Inc.. For how StockDrifts scores these disclosures, see the Japan insider signal tier research, or browse every Japanese stock we track.