On Wednesday morning, Japanese prosecutors released former Toyota Motor Corp. executive Julie Hamp without charges, capping 20 days of headlines about her arrest. Hamp was not only the first non-Japanese Toyota executive to be based in Japan, but until recently its highest-ranking female official.

In June, Hamp, then the company's top communications officer, was arrested for allegedly importing the painkiller oxycodone, which is tightly controlled in Japan. Then last week, she resigned from her job.

Hamp's resignation was described in multiple outlets as a setback — not only to Toyota's own efforts to diversify, but to Japanese Prime Minister Shinzo Abe's. The prime minister has said he wants women to hold 30 percent of leadership roles by the end of the decade. He's also spoken of a seemingly more doable task, asking in a speech that all companies have at least one female executive.

But a "setback" implies there has been significant progress, when in reality the numbers of women in senior roles in Japan are still extremely low. In Japan, even a goal of companies having one top female executive may be harder than it seems.

A 2014 study shows how rare female executives really are, which was why Hamp's appointment in April was so groundbreaking. Last year, the 20 largest companies in Japan had 230 executive committee members, or managers who report directly to the CEO, according to the report by 20-first, a U.K.-based consultancy that works with companies on diversity issues. Of those 230, just two were women. At the time, only Japan Post Holdings and Sony had a woman among their top ranks, and both were in staff roles rather than managing operational businesses.

While those numbers are not surprising — Japanese business culture has long been fueled by traditional gender roles — they are still eye-opening. Women hold just 3 percent of board seats in Japan, which means it ranks dead last among 20 major economies, according to the research organization Catalyst.

Other data from 2013 found that only 15 percent of Japanese companies have any female executives at all. Japan also has the lowest share of women parliamentarians of all OECD countries, according to a recent report.

The progress is incredibly slow. Reports have shown the percentage of Japanese women in all managerial jobs is just over 10 percent — a number that barely budged between 2005 and 2011. Even Yoko Kamikawa, who served during Abe's first term as his minister of gender equality in the mid 2000s, told the Economist last year that she is startled by the lack of progress for women.

Some pundits have questioned whether Hamp's resignation could have a chilling effect on attracting foreign managers to Japan to help diversify the company's ranks. Perhaps the more pressing question, though, is whether it could have that effect on women. The country still has a very long way to go to reach even a single token female at many of its companies, much less meet Abe's increasingly unlikely goal of getting them into a third of all leadership jobs.

Read also:

Like On Leadership? Follow us on Facebook and Twitter, and subscribe to our podcast on iTunes.