A
Anime - Japanese word for "cartoons", used by non Japanese speakers to specifically refer to Japanese cartoons.

B
Bokken - Wooden sword

C
-Chan - a name suffix in Japanese used to indicate familiarity toward a girl or young child. Something of an insult if used otherwise.

G
Gaiden - Side story, usually focusing on a particular character.

H
-Han - Name suffix that is the kansai dialect's equivalent to "-san".
Hotaru - Firefly

I
Ichizoku - Family, clan

K
Kagemusha - Shadow warrior, body-double
Kansai-ben - Dialect used in the Kansai/Osaka region that is known for being slangy. Used by Benitora and Chinmei. Usually dubbed (much to the chargrin of many) as a Southern American dialect.
Kodachi - Short hand sword
-Kun - name suffix in Japanese used to indicate familiarity toward a young man, boy, or rarely, but not never, toward a girl.
Kunoichi - Female ninja, what Mahiro is.

M
Manga - Japanese for "comics", used by non Japanese speakers to specifically refer to Japanese comics.
Manga ka - Japanese for "comic artist", used by non Japanese speakers to specifically refer to one who creates Japanese comics.

S
-Sama - Name suffix in Japanese used to indicate extreme respect or a higher status. More formal than the English Mr. or Ms. Often translated as "Lord".
-San - Name suffix in Japanese used to indicate unfamiliarity or respect. A bit less formal than its closest English equivalent, Mr. or Ms.
Sendai - Former, of the previous generation
Sengoku jidai - The Warring States period, a time of social upheaval, political intrigue, and nearly constant military conflict in Japan that lasted roughly from the middle 15th to the early 17th century. Shingan - The mind's eye
Shuriken - Throwing stars