# Septeni Holdings

Septeni Holdings is a Corporate Investor based in Tokyo, Japan.

## Overview

- **Organization type:** Corporate Investor
- **Headquarters:** Tokyo, Japan
- **Region:** Asia
- **Address:** Tokyo, Japan
- **Founded:** 1990
- **Assets under management:** Undisclosed
- **Website:** septeni-holdings.co.jp
- **LinkedIn:** https://www.linkedin.com/company/septenigroup

## Regulatory record

- **Reports private funds:** No

## About

Founded in 1990 by Mamoru Nanamura, Septeni Holdings emerged as an early internet marketing firm in Tokyo before evolving into a holding company structure. The firm remains publicly listed in Japan, with Dentsu Group Inc. holding a 52.01% voting stake. Nanamura retains a significant individual shareholding of roughly 10.5%, while Hong Kong-based Oasis Management Co. Ltd. holds approximately 10% as a co-investor, creating a governance triangle that blends founder control, strategic parent influence, and external institutional oversight. Septeni deploys capital across digital advertising services, media platforms, and a set of non-core operating assets that reveal a preference for tangible, community-anchored investments. The group's core internet marketing business serves as the cash engine, while the portfolio extends into real estate ventures such as the HOMMA Smart Community residential project in Portland, Oregon, and KDDI HOSTY smart hotels in Japan. Sports assets include the Tokyo United Basketball Club and Sint-Truidense VV, a Belgian professional football club. The firm operates through subsidiary companies spanning Japan, the US, and Belgium. Japan remains the operational and revenue center, while the US office in Portland supports the HOMMA real estate development. In May 2026, Septeni was recognized with the "Best Ads Account Growth Award" and "Best Direct Award" at the LINE Yahoo Partner Award 2025 H2, underscoring the continued competitiveness of its core digital advertising unit. The group also maintains professional affiliations with Japan's Association of New Economy, the Japan Advertising Agencies Association, and the Japan Internet Advertising Association, embedding it within the domestic digital commerce ecosystem. What distinguishes Septeni is its dual identity: a publicly traded digital marketing operator that is also a parent-level allocator into operating businesses far outside the typical ad-tech perimeter. The presence of Dentsu as a majority stakeholder and Oasis Management as an activist-aligned institutional holder creates a permanent tension between strategic patience and return discipline. Meanwhile, the Nanamura family's sustained boardroom presence ensures that entrepreneurial bets — including a Belgian football club — survive quarterly earnings cycles.

## Sectors

- Media & Entertainment
- Real Estate
- Sports, Media & Entertainment
- Education

## Offices

- Portland, Oregon, USA

## People

- Mamoru Nanamura — Founder
- Dentsu Group Inc. — Parent company (52.01% voting rights)

## Questions

### Who runs investment decisions at Septeni Holdings?

Strategic oversight rests with the board and parent company Dentsu Group Inc., which holds 52.01% of voting rights. Founder Mamoru Nanamura retains roughly 10.5% equity and ongoing influence, while institutional investor Oasis Management holds approximately 10%, bringing external governance pressure. Day-to-day capital allocation decisions are embedded within the holding company's executive team rather than a standalone investment committee.

### How is Septeni Holdings related to Dentsu?

Dentsu Group Inc. is the majority shareholder, holding 52.01% of voting rights in Septeni Holdings. The relationship makes Septeni a consolidated subsidiary of Dentsu, integrating its internet marketing capabilities into Dentsu's broader advertising and media network while preserving Septeni's separate public listing and operational independence in adjacent ventures.

### What is the significance of Oasis Management's stake in Septeni?

Oasis Management Co. Ltd., a Hong Kong-based activist investment firm, holds approximately 10% of Septeni Holdings. This stake introduces an external governance dynamic, as Oasis has a track record of pushing for capital-efficiency improvements at Japanese listed companies. Its presence adds a layer of institutional discipline to a boardroom otherwise shaped by founder and parent-company interests (Altss estimate).

## Related profiles

- [Sepides Gestion](https://altss.com/profile/sepides-gestion)
- [Septwolves Holding](https://altss.com/profile/septwolves-holding)

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Last updated: 2026-08-11T02:43:31.692Z

Canonical page: https://altss.com/profile/septeni-holdings

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