SPOILERS
Summer, Heian period related terms
Shouryaku 5th Year 正歴五年
The Japanese have a way of naming years. Each small period is denoted by a name, in this case Shouryaku (正暦), and then by a year (5th year). The first year in a period is called the Gannen (元年). Shouryaku starts in 990, so the fifth year would be 994. This is apparently when the story starts. Names have now become names of the current Emperor, whereas in older times, major events can bring about a new period. For example, portents, disasters, etc. will also change the period.
響無鈴（こなれ）
Literally, bells that give off no sound? Kanna has these in her hair. ![[WWW]](/~zalas/AIR/wiki/AIRmodern/img/moin-www.png){kind=small}
A fan site seems to say that it's a made up word and that it's a bell filled with jade.
袴（はかま）
Kanna I think is wearing the belt from one of these. They're traditional Japanese clothing. This site shows you what a hakama looks like. Traditionally, red hakamas were characteristic of the miko (Shinto Shrine Maidens).
長太刀（ながだち）
A long sword. Ryuuya has an iron one of these...
正八位衛門大志
Shouhachi (正八) is a rank / class. The Emonfu (衛門府) were an order of guards to guard the gates of Heiankyo (?) Basically Ryuuya is a guardsman of moderate standing. However, one inaccuracy is that the Emonfu were split into Left and Right side groups about a hundred years ago, and Ryuuya doesn't seem to indicate which Emonfu he is from.
Nephillim- <strike>Cross-referring to the PS2 voices (Daisakan- 大左官) and the appropriate Kanji characters for it, it seems that he belonged to the Left. The characters for it don't correspond to the text of the PC game</strike> Haeleth's right. I probably heard 大志官 ;
But the phrase 大左官 does not appear in the text of the PS2 version. 正八位衛門大志 is the PS2 text; the PC version reads 衛門正八位大志 - Haeleth
Wakasa 若狭（わかさ）
Ryuuya says he's originally from the outskirts of Wakasa. According to Map of Heian Japan, Wakasa was a province near modern day Wakasa Bay (and is in the same area today as part of the Fukui Prefecture <福井県>) However, there is also a small town called Wakasa that is in modern day Japan and is around 250 km northwest of Kobe.
唐天竺
China and India, or a phrase to refer to any far off place.
余(よ),お主(おぬし),妾(わらわ),麿(まろ)
Archaic personal pronouns; Kanna uses "yo" to refer to herself and "onushi" to refer to Ryuuya. That this speech pattern is strange is made clear later on when Ryuuya asks why she doesn't use "warawa" and "maro" instead.
passerby from 2ch- The reason why Ryuuya said Kanna's "yo" was strange is that "yo" is a first person pronoun for adult men. "warawa" is for adult(mature) women, and "maro" is for kids(mostly boys, I don't know whether it's used by girls). Also consider that in medieval Japan a person was considered an adult in his/her early teens.
五穀豊穣の願(ごこくほうじょうのがん)
Kanna chants this. 五穀 refers to the five major grains. This is basically a prayer hoping for a bountiful harvest.
神奈/神奈備様/神奈備命
Uraha and Ryuuya refer to Kanna as just Kanna (with suffixes, etc.), but the other servants seem to use Kanna Bisama while her full name is Kanna Binomikoto. Apparently the "no mikoto" suffix is used as an honorific for the gods. According to the Kojien, the "no mikoto" suffix was used in the Kojiki as an honorific for the gods and sometimes for nobles also and may have been used during the early Heian era.
Midsummer's Day 土用の大暑
This is when Kanna has to perform that harvest ritual.
十二単衣 (じゅうにひとえ)
This type of clothing is packed into Kanna's luggage. A shinto shrine site has pictures of this. It seems to have the look of 12 layers of cloth.
十二単 is what people in later times called the clothing wives wore in the Heian era. Thanks to 海外葉鍵事情 二ヶ国目の167氏.
五衣 (いつつぎぬ)
This seems to be a 5 "layer" variant of the juunihitoe. This has some pictures of them.
儀仗用の平鞘太刀(ぎじょうようのひらざやたち)
A better description of Ryuuya's sword. So it's a Guard's Flat Scabbard Long Sword?
吾妻(あずま)
It's a town in modern day Gunma prefecture, Kozuke province in Old Japan? Supposedly rebel forces during the period in question resided there.
Furthermore, it's used to refer to the Eastern provinces in general, like the land to the east of Izu(13) ( http://www.samurai-archives.com/map.html). Thanks to 海外葉鍵事情 二ヶ国目の167氏
国衙(こくが)
When they wanted to cross a river, they may have to get close to this place, which is more populated. Yahoo Japan gives a map. Apparently this place is at: 兵庫県 > 三原郡三原町 > 神代國衙の周辺地図. The river they're trying to cross may be modern day 牛内川. That place seems to be on a small island 70km southwest of Osaka
There is another 国衙 called 近江国衙跡 which is located very close to Kyoto (12km east). This is next to a large river called 瀬田川.
Furthermore, Kokuga also means a government office (the capitol of an old province), which seems to be the case. They're probably referring to a kokuga in Kii province or some other nearby province. During their travel to Koyasan, they comment that it took them a month, which means it IS likely that the kokuga they are referring to is the 近江国衙跡
雅楽(ががく)
Old Japanese court music is what EDICT gives. They played this at the festival in the little town Kanna & co. passed.
斑鳩(いかるが)
Ikaruga is the place where Shotoku-taishi's palace was supposed to be. Currently the location of Houryuuji (法隆寺). In modern-day Nara Prefecture.
Further south beyond this is a 金剛. That doesn't mean diamond in this case, but rather the Buddhist symbol 卍. The map probably indicates Buddhist temples with that symbol.
真言の霊山(しんごんのれいさん)
Also on the map. しんごん might be referring to 真言宗, a Buddhist priest who founded 高野山.
高野山、金剛峰寺
Also on the map 高野山 is a mountain in Wakayama prefecture according to EDICT. Wakayama prefecture is one prefecture south of Osaka. Amazingly enough, this mountain is a Buddhist mountain and a tower burned down due to lightning in AD 994, according to the nenpyou. There is also a building called the 金剛峯寺 there. The mountain is about 45 km south of Osaka.
注連縄(しめなわ)
Kanna and co. come across this when they are near/on Koyasan. It seems to be a warding off rope.
薙刀(なぎなた)
A halberd.
八百比丘尼(やおびくに)
Monk soldier asks if they are meeting up with this person. Bikuni means some sort of priestess, and it seems that this is referring to Kanna's mother. Yaobikuni is also a legend. The legend tells of an immortal woman and the people who became jealous of her. The page indicates that the place where the legend takes place is very close to Koyasan, and it is most likely that the writers at Key manipulated this into Kanna's mother.
Other glossaries
This page has extensive glossaries (in Japanese) for each of the chapters of Summer; scroll down to find them.