SNA (Tokyo) — One of the most prominent conservative lawmakers resigned this evening from the leading opposition Democratic Party. Akihisa Nagashima served as a parliamentary vice-minister of defense for the Yukio Hatoyama and early Naoto Kan cabinets, and is one of the very closest of all Japanese lawmakers to the US foreign policy and defense establishment. Indeed, it is sometimes difficult to tell if the US-educated Nagashima more represents Tokyo to Washington or Washington to Tokyo.

Aside from his role as a primary political link with the US “alliance manager” community, in domestic politics he has positioned himself close to the political right. He is a regular visitor to Yasukuni Shrine and is openly affiliated with the revisionist lobby Nippon Kaigi.

Nagashima’s departure from the Democratic Party distinctly weakens its most conservative wing, leaving figures such as Seiji Maehara and, to a lesser extent, Goshi Hosono more isolated as the party’s small coterie of pro-US conservatives.

The silver lining is that this may open the door for the Democratic Party to begin to find a greater degree of ideological coherence as a center-left organization that can offer alternative perspectives to those of the Abe regime. But that will still require becoming a smaller party before there is a prospect of rebuilding.

Nagashima used his Twitter feed to explain his decision as follows: “As I am one who has pursued true conservative politics, fighting as comrades alongside the Japan Communist Party, with whom I have enormous differences in values, is crossing a line that is simply too far.”

While Nagashima is no doubt sincere in his denunciation of Democratic Party electoral cooperation with the Japan Communist Party, he left a likely second reason for his departure unsaid.

His electoral district is the Tokyo 21st District (Tachikawa, etc.), and shortly before resigning from the party he resigned as secretary-general of the Democratic Party’s Tokyo Chapter. That is the same DP Tokyo Chapter that has lost almost 20% of its Tokyo Metropolitan Assembly candidates to defections to Governor Yuriko Koike and appears set for a cataclysmic electoral defeat in July. Indeed, earlier in the day, the Japanese media thought that Nagashima was resigning only from his secretary-general position in order to “take responsibility” for all the candidate defections.

Now it appears much more likely that Nagashima will serve as an independent lawmaker while he awaits the chance to join Governor Koike when her movement enters national politics. From an ideological perspective there is no big gap between Nagashima and Koike. They would probably see eye-to-eye on most major political issues.

Akihisa Nagashima might, then, even be seen as the first national level defection from the Democratic Party to Governor Koike. If so, he likely won’t be the last one.