Japanese culture:


Christmas in Japan: http://www.japan-guide.com/e/e2299.html

Kentucky Fried Chicken as a popular Christmas dinner in Japan: http://en.wikipedia.org/wiki/KFC#Japan

Izakaya (a type of restaurant/bar): http://en.wikipedia.org/wiki/Izakaya

Wagashi (Japanese confectionery): http://japanesefood.about.com/cs/dessertssnacks/a/japanesesweet.htm, en.wikipedia.org/wiki/Wagashi

Ritual Japanese phrases not easily translated into English, such as "ittekimasu" and "itterasshai" and "yoroshiku": http://www.mangalife.com/features/WordsofTruthandWisdomYoros.htm

(Most of these don't actually appear in the manga, but might be useful as cultural references for fanfics. The ritual phrases probably do, although they may not be recognizable as such in the English translations.)



Places where the Harudaki characters live:


Niigata, residence of the Iwaki family (Book 3, "First Cry"): en.wikipedia.org/wiki/Niigata_Prefecture, http://www.enjoyniigata.com/en/index.html. A TV news report mentions that the Iwaki family resides in Niigata.

Mita, Minato, where Onozuka apparently lives (Book 11, "Emergency Door"): http://en.wikipedia.org/wiki/Mita,_Minato,_Tokyo. There are actually two neighborhoods called "Mita" in Tokyo, but Onozuka tells the taxi driver to go to "the neighborhood at Keidai Seimon in Mita". A google search shows that this seems to be a reference to the Keio University Main Gate (Keidai Seimon Mae), which is located in Mita, Minato: http://shirokanelc.net/map.aspx

Meguro, Tokyo, where Miyasaka lives (Book 11, "Emergency Door"): http://en.wikipedia.org/wiki/Meguro,_Tokyo. Onozuka first tells the driver to take him to Mita, then changes his mind and goes to Meguro to visit Miyasaka.



Links relating to the people and events in Fuyu no Semi:


Tokugawa Shogunate: http://en.wikipedia.org/wiki/Tokugawa_shogunate, http://www.japan-101.com/history/history_tokugawa_shogunate.htm

Tokugawa Shogunate/Edo Era: http://www.japan-guide.com/e/e2128.html

Keiou Era: http://en.wikipedia.org/wiki/Kei%C5%8D

Meiji Era: http://en.wikipedia.org/wiki/Meiji_era

The Republic of Ezo: http://en.wikipedia.org/wiki/Republic_of_Ezo

The Boshin War: http://en.wikipedia.org/wiki/Boshin_War, http://wiki.samurai-archives.com/index.php?title=Boshin_War

The Battle of Hakodate: http://en.wikipedia.org/wiki/Battle_of_Hakodate

Choshu Han (Choshu Domain): http://en.wikipedia.org/wiki/Ch%C5%8Dsh%C5%AB_Domain

Sufu Masanosuke: http://red-bird.org/meiji/sufu.htm

Sonnou joui: http://en.wikipedia.org/wiki/Sonn%C5%8D_j%C5%8Di, www.samurai-archives.com/snj.html

Koku: http://en.wikipedia.org/wiki/Koku



Non-internet reference:


The book "Shinsengumi: The Shogun's Last Samurai Corps" by Romulus Hillsborough (Tuttle Publishing, c2005, ISBN 0-8048-3627-2) is an informative accounting of the fall of the Shogunate, although it focuses mainly on the Shinsengumi, who do not appear in Fuyu no Semi. (The Shinsengumi were a special police force that was developed to protect Kyoto and combat the Shogunate's enemies towards the end of the Edo Era.) It does mention the history of the Choshu Domain and how that led to their involvement in the overthrow of the Shogunate.

The information on "koku" I actually got from the 2002 NHK taiga drama "Toshiie to Matsu" ("Toshiie and Matsu"), but I also added the Wikipedia link for additional information, and since it's kind of hard to link to a TV show.

EDIT: Sorry, it seems that a few of the links didn't format properly, but they should work if you cut and paste them into the browser.