Shogakukan
I just noticed that Tinker Tailor Soldier Spy (the unforgivably disencommaed movie adaption of Tinker, Tailor, Soldier, Spy has the Japanese title Uragiri no sākasu 裏切りのサーカス, "Circus of betrayal".
The original novel has always been simply Tinkā, teirā, sorujā, supai, so this represents a change in expected audience, naming conventions, or both. My money's on the former, based on the hypothesis that Japanese people reading books by John le Carre are doing so at least partly out of Anglophilia, and thus welcome exposure to English nursery rhymes they wouldn't otherwise know, while the movie promoters are afraid that leaving the first half of the title completely opaque (even English-speaking people barely remember what a tinker is) will discourage potential viewers.
Sidebar: The Spy Who Came in from the Cold is translated Samui kuni kara kaette kita supai 寒い国から帰ってきたスパイ, "The spy who came back from a cold country." This is a bit unfortunate in a couple of ways.
First, the fact that you can't use adjectives as substantives in (contemporary) Japanese means that the delightful ambiguity of "the cold" has to become "a cold country" (I suppose samusa could have been used, but combining that with kaeru that feels unidiomatic to me — "the spy who came in from the coldness").
Second, and related, the Japanese calque for "cold war" was 冷戦 — different character for "cold." I'm sure most readers figured it out, but the upshot is that no way was found to recreate the original title's balance of simplicity and depth.
Completely unrelated and extremely nerdy: An interesting (if unfortunately unfriendly on one side) exchange took place on japanese.stackexchange.com yesterday. To summarize, the publisher Shōgakukan prefers to render its name, in both kana and Roman characters, as shown at left — that is, in a way that preserves the etymology: shōgaku 小学 "elementary school[ing]" + kan 館 "house" (they started out publishing materials for elementary school-age kids). But the name is actually pronounced shōgakkan, same way that gaku 学 + kō 校 = gakkō 学校, "school." So we see citations like this on WorldCat: the Shogakukan progressive English-Japanese dictionary, published by "Shōgakkan."
On the other hand, it's not hard to find another entry for the book on WorldCat which gives "Shogakukan" as the publisher, and we can also find the Shogakukan Random House English-Japanese dictionary, published by "Shogakukan" (note no macron either!) but attributed to "Shōgakkan," along with Random House. So clearly WorldCat entries are not going to prove anything.
It seems to me that this is basically a style guide issue: do you romanize a publisher's name (as opposed to a book's title, or a personal name) strictly according to pronunciation, or do you use their preferred spelling? I had a quick look in the MLA Style Manual and couldn't find anything on this issue specifically, although we are advised to "follow known preferences" when romanizing Chinese and Japanese personal names. Do other commonly-used style guides prescribe more specific rules for "Shogakukan/Shōgakukan/Shōgakkan" situations?
Leonardo Boiko:
I’d go with the publishing house’s official spelling, but only because that’s presumably what they’ll use in their own books if they ever print romanized bibliographic information. I generally try to preserve the ortography of the original editions. In an ideal world, databases like WorldCat, Librarything etc. would then have extra information on alternative spellings (as aliases) pointing to the same publisher, author etc. (which is also a desirable feature to relate various transcriptions in the original writing system and romanizations).