Heian Terms:

ayakashi: also, youkai. spirits, kitsune, demons, etc. think Spirited Away.
dairi: the far back middle section of the capital where the emperor lived and politics were played.
-dono: at the time, probably used for people of the same rank and below.
kebiishi: (traditionally spelled 'kebiwishi') very much like a police officer and judge rolled into one.
kimi: a designation of high rank. sir, or lady, I suppose.
kizoku: nobility, aristocracy.
magatama: a piece of jewelry made of metal or precious stones, often times of a half-yin-yang-like shape or that of a teardrop. They were believed to hold mysterious powers of protection.
(For a nice picture see www(.)infonix.biz(/)magatama(/)top(.)htm)
mikado: emperor.

Dictionary and Notes:

gomen: "sorry." (gomen ne, gomen na, gomen nasai are all basically the same thing. I won't get into the feeling difference between them.)
itazura: bad joke or prank.
kouhai: see senpai.
manjuu: pancake/waffle thingy with An (adzuki bean) inside.
o-mamori: charm or amulet.
omiyage: frequently translated as 'souvenir,' it