Useful Japanese Terms                                                                                               
Arigato: Thank you (Domo Arigato gozaimasu = Thank you very much)

Baka: stupid, fool

Bishoujo: Beautiful/Pretty girl (shoujo = girl)

Demo: but

Doko(ni): Where?

Domo: very much

douitashimashite: You are welcome

Ecchi: mildly hentai (see below) risque`

Eigo: English

Fuku: clothes, uniform, (i.e.: sailor fuku)

Gomen(nasai): sorry

hai: yes

hamusuta-: hamster

henshin: transformation

hentai: sexually perverted, a pervert

Hiragana: One of the Japanese phonetic alphabets, used for native terms

Iie: no

ja ne: bye (colloquial)

Kanji: Chinese characters as used in Japanese w/different meanings etc.

kawaii: cute

kira-: killer

konnichiwa: good day, hello

kowai: scared, afraid/scary

kouro: run

kudasai: please (ocha kudasai =  tea please)

kyojin ika: giant squid

Manga: Japanese Comics

migurushii: ugly

minna: everyone

nani: what?

ne: added to the end of a sentence to mean "isn't it?" or "Am I right?"

Ohayo: Good morning (more polite to say ohayo gozaimasu)

omaesan: you, my dear, hey

Onegai: please, when making a request

Otaku: literally means you, but we use it to mean anime fanatic!

Otou-san: father

Owari: end/finale

Piku: to shake or tremble or a common anime face fault
I do not claim to be an expert at this, but I know these terms are usually (I say usually, because there are a few that aren't) very helpful. If I make mistakes in spelling, you might tell me or something...that would be very nice. Enjoy!