A on a topic most Japan scholars takes entirely for granted: 

the preservation of documents, books, and other historical materials in the face of incendiary raids that laid waste to urban Japan.

tl;dr: as if it needed to be said, god bless librarians.

Understandably, efforts to gauge the toll of the firebombings on urban Japan have centered on human casualties.

When compared to the tens of thousands of civilian lives lost and the millions left homeless, the destruction of books, papers, and artifacts feels trivial.

That said, reflecting on this campaign through the lens of historical preservation tells us more than one might think about Japan's own air defense system.

Amidst the ruinscapes that defined urban Japan, after all, were countless libraries, archives, and research institutes.

To the extent scholars have examined this topic, they have scrutinized the so-called "Wagner List": the list of culturally significant sites identified by art historian Langden Wagner for preservation.

Although Wagner is most often remembered as an advocate for sparing Kyoto from bombardment, this list reveals a much wider range of priorities.

Thanks to Nakanishi Yutaka (to whom this thread is greatly indebted), we now have an exhaustive analysis of the fate of his list:

As a quick glance makes clear, the vast majority of its items was indeed spared destruction. 

There was, however, one clear exception: castles.

For obvious reasons, castles formed orienting points for sorties flying night-time raids. Intentionally or not, many were destroyed.

Libraries, archives, and research centers, by contrast, went largely unscathed. Apart from collections at the Osaka Imperial University Medical School and the Tokyo Imperial University Engineering Campus in Chiba, Japan's historical records fared exceedingly well.

Why? Nikanishi identifies four primary reasons. 

1) The relocation of materials and even entire collections to the countryside. No sooner did the Doolittle Raid destroy parts of the capital in 1942 than librarians and archivists began to prepare to evacuate collections.

In part, this was done for the sake of historical preservation. Partnerships with prefectural libraries and colleagues in the countryside allowed major library holdings to ship huge volumes of materials to rural storehouses.

This was no small feat of logistics.

So, too, were these efforts motivated by the exigencies of civil air defense.

In Osaka, for example, four of its municipal branch libraries were repurposed into nurseries and emergency air raid shelters. Much of their collections were relocated to accommodate this conversion

2) The heroic efforts of library staff.

Anyone who has done research at Waseda Uni. owes a debt of gratitude to Yamakawa Yoshitaka (sp?) and his son, two overnight guards who, on the evening of May 25, led the effort to extinguish fires in its main library and theater museum.

3) Architecture.

Crucially, in contrast to the wood that defined the urban built environment, central libraries were often built with concrete. This helps explain why so many parts of Waseda Uni. could have burned while its main library facilities went unharmed (see map)

4) Luck.

The firestorm that enveloped Tokyo on March 9/10 knocked on the front door -- the red gate -- of Tokyo Imperial University's Hongo campus, but never entered.

It very well could have, and would have spelled the destruction of all sorts of research treasures.

In the end, the real gap in the historical record comes as a result of the burning of documents by Japanese military and government officials -- not as a result of the firestorms whipped up by B-29s.

My takeaway: buy your librarians and archivists a drink the next chance you get.

Now more than ever, as they keep our research agendas running against the backdrop of a different sort of crisis.

For more on this, see Nishitaka's work here: https://ci.nii.ac.jp/naid/110007860978