Stephen Givens is a corporate lawyer based in Tokyo.

A statistical analysis of outside directors at Japanese listed companies confirms what the eye sees -- the same old faces keep reappearing in multiple and overlapping boards like Wally in the Where's Wally series.

Data gleaned through the GoToData database of the nonprofit Board Director Training Institute show that there are at least 342 directors who hold board seats at three or more companies, of which 100 sit on at least one company among the 100 largest by market capitalization. This is the pool of big-league repeaters with heavily subscribed dance cards.

In turn, the 342 repeaters sit on the same boards with their fellow members of the same pool. Of the 342 board seats, 137 occupants overlap with two or more repeaters, just as the same roster of high society guests are repeatedly invited to the same parties given by different hosts.

To illustrate the phenomenon, consider the following five companies: Japan Post Holdings, Japan Exchange Group (JPX), Mitsui & Co., Omron and Tokio Marine. Now also consider the following five names: Akio Mimura, Nobuhiro Endo, Eizo Kobayashi, Izumi Kobayashi and Masako Egawa.

Some combination of two or more of these five individuals sit as outside directors on the boards of all five companies.

Just who are these popular repeaters? The answer is not surprising when one considers the required conditions on the demand side and capacity constraints on the supply side. The repeaters tend to be either elderly corporate statesmen or women recruited to satisfy the now mandatory diversity quota.

Three of the five individuals are archetypal corporate statesmen: Nippon Steel chairman Akio Mimura, 80; Itochu emeritus director Eizo Kobayashi, 72; NEC chairman Nobuhiro Endo, 67.

Mimura serves as outside director at Japan Post and Tokio Marine, and is also chairman of the Japan and Tokyo Chambers of Commerce. In addition to directorships at JPX -- parent company of the Tokyo Stock Exchange -- and Omron, Eizo Kobayashi is also an outside director at Japan Airlines. Endo has outside director seats at three companies including JPX and Tokio Marine.

Masako Egawa (Photo by Yoshiaki Inoue)

The other two repeaters are women. Unlike the elderly statesmen, they did not spend decades in a Japanese company climbing the corporate ladder, with both spending their early years in U.S. investment banks.

After earning an MBA from Harvard Business School, Masako Egawa, 66, segued into a career as an academic administrator at Tokyo University and as a business school academic at Hitotsubashi University. After as CEO of Merrill Lynch Japan from 2001 to 2008, Izumi Kobayashi, 62, has held a series of outside directorships at companies such as All Nippon Airways, Mizuho Financial Group and Mitsui & Co.

Egawa and Kobayashi are two examples of a cluster of properly credentialed women who occupy seats on multiple overlapping boards.

Other notable female repeaters include business consultant Sakie Akiyama, 60, who currently holds seats at Sony, Orix, Mitsubishi Corp. and Japan Post, along with two of the three elderly statesmen named above, Nobuhiro Endo and Eizo Kobayashi.

Egawa's Hitotsubashi Business School colleague, Christine Amadjian, 63, holds positions at Mitsubishi Heavy Industries, Sumitomo Electric, Asahi Group Holdings and, once again, JPX.

Izumi Kobayashi (Photo by Tetsuya Kitayama)

On the positive side, it must be conceded that the repeater phenomenon by definition occurs on boards that have a lot of outside directors, in many cases a majority of the full board. Unlike most, these companies -- to their credit -- are going beyond the bare minimum requirement of having two outside directors.

Still, one naturally wonders whether it is possible for an outside director to dig very deeply into a company's corporate practices while they sitting on the boards of three or more top companies, in addition full-time corporate or teaching jobs.

Proxy advisers like Institutional Shareholder Services (ISS) and Glass-Lewis, as well as institutional investors such as BlackRock and Vanguard, are adopting increasingly stringent standards against "overboarding." Typically, the standards in place today require a negative vote against an incumbent CEO who sits on more than two other boards.

Beyond simple overboarding looms the larger question of inbreeding -- why do so many large companies invite the same cast of characters to sit as "independent" directors on their boards?

Is it possible that a reputation for not making waves or asking hard questions fits the profile that management favors in an independent director? Or, to borrow a Warren Buffett simile, does a Cocker Spaniel receive more board invitations than a Pit Bull Terrier?

As one example, the degree of inbreeding at JPX should raise eyebrows and questions, especially in light of JPX's responsibility as parent of the Tokyo Stock Exchange, the standard-bearer of corporate governance reform in its capacity as the official source of the Corporate Governance Code.

The recent awkward revelation that JPX has for years used Heiwa Real Estate, owner of the Tokyo Stock Exchange Building and JPX's landlord, as a convenient amakudari, or descent from heaven, landing spot for retired Tokyo Stock Exchange executives invites further speculation. What did JPX's independent directors know and what did they do about it?

Of course, this extreme degree of overlap may simply be the inevitable result of a limited pool of qualified candidates. Still, it would inspire greater confidence if one heard more about dissenting views on Japan's corporate boards.

Resignations like those of Fast Retailing founder Takashi Yanai and Nidec CEO Shigenobu Nagamori from the board of SoftBank Group in 2019, clearly signaling disapproval at the direction being taken by SoftBank founder Masayoshi Son, should happen more often.

Then again, Yanai and Nagamori, unlike most of the familiar faces serving as outside directors, are maverick billionaires who can afford to speak their minds.