Pachinko - A Japanese vertical pinball game. Its is both a form of recreational arcade game and much more frequently as a gambling device, filling a Japanese gambling niche comparable to that of the slot machine in Western gaming. In short: for the Japanese it is more than just a pinball game.
A pachinko machine resembles a vertical pinball machine, but has no flippers and uses a large number of small balls. The player fires balls into the machine, which then cascade down through a dense forest of pins. If the balls go into certain locations, they may be captured and sequences of events may be triggered that result in more balls being released. The object of the game is to capture as many balls as possible. These balls can then be exchanged for prizes.
Pachinko parlors are widespread in Japan, and they usually also feature a number of slot machines (called pachislo or pachislots); hence, these venues operate and look similar to casinos.
By concentrating on the flickering lights, the little balls as they fall down into the machine and the sounds, the player can get into some sort of meditational trance much like monks and priests when they are meditating in a shrine. Characters in anime and manga series are sometimes seen playing pachinko when they are troubled by something or when they are in some kind of emotional dip. By playing pachinko they try to regain their inner balance and gather the emotional strength to resolve or at least face their problem.
Ohayo Gozaimasu - Good morning. Standard greeting used by people when they meet for the first time in the morning at home, on the way to work or school or as the working day begins. Bar hostesses will use this to greet eachother as they come to work in the evening. You reply to it by repeating it back! In informal speech it is abbreviated to "Ohayo".
Oppai - Breasts/Boobs. It also can mean slang for "Mother's Milk".
Otaku - Die-hard fan, nerd in Western World, but mostly Unhealthy Obsessive Interests in Japan. In Western Europe and the US some people call themselves, with a certain pride, "otaku" to indicate that they are anime fans. In Japan however otaku has not only a broader meaning but it is also used in a negative sense.
In Japan, an otaku is a social outcast, a pariah of sorts. A loner with a certain obsession for which he sacrifices everything else. That obsession can be anime and/or manga but it can also be something else like cars, an idol singer, a photo model, an theatre performer, a sportsman, ... . Take an idol singer otaku for example. He must absolutely have everything that is related to her. He must also know everything about her, even the smallest details such as to which elementary school she went when she was still a kid. Nothing else really matters.
He will meet with fellow otaku on a regular basis and they will try to beat each other with the size of their collection and the extent of their knowledge. Occidental examples of otakus can be found, for example, among the Trekkies (fans of Star Trek).
Joudan - A joke!, I'm just kidding. Can also be used as an expression of disbelief: "You've got to be joking!". Like "Joudan deshou?"="Are you kidding?".
Itai - Ouch!, That hurt!, painful, its sore!. Used when the speaker feels sudden pain of some sort.
Irasshaimasu - Welcome, although the literal translation is "Be here". This standard welcome phrase is said to all costumers when they enter the store/restaurant/kissaten/etc. It is an honorific verb (ie only used to people socially above you) that literally means "to be (in a place)". The real feeling here is something like "Honour us by coming into our humble establishment".
Gesen - Abbreviation for Game Center Crown. The place run by Motoki where the senshi tend to hang around in their free time, especially Usagi and Minako. In the manga their headquarters is under the Gesen.
Ecchi - Lewd, indecent, H. "Ecchi" is the pronounciation of the letter "H" which is the first letter of Hentai. Ecchi is more mildly than hentai. It can be used in a more positive sense by a girl. Mostly when she has feelings for the boy in question and/or in a situation where "she only defends herself with words" if you know what I mean ^_^.
Fuketsu - Unclean, Dirty, Filthy, Impure. [Shin Seiki Evangelion]: Maya's comment when Misato and Kaiji are found in an elevator in a,
Fuku - Clothes, good fortune, ... . "Fuku" has many uses depending on its kanji writing it also can mean, "to wipe","to mop". If you only have the kana writing you'll have to look at the context to determine the correct translation.
Ai - Love, together, accomplice, ... "Ai" has several uses depending on its kanji writing. If you only have the kana writing you'll have to look at the context to determine the correct translation. [Sailor Moon]: "Aino Minako" although it is a name literally means Minako of love.
Akuma - Devil, demon, satan.... Can also be used to refer to a living thing, much as the English would say: "You devil". The Japanese word akuma means "Demon, Devil; Fiend; Satan; Evil spirit" and is composed of "evil; bad; wrong" and "witch; demon; evil spirit". Japanese nouns have no grammatical number or gender. So akuma is both singular and plural which means that akuma refers to a single Demon as well as to several.
Arigatou Gozaimasu - Thank you. Used to express gratitude after the speaker has recieved something. This can either be an object or a favor of some sort. In informal speach this is often abbreviated to "Arigatou". In formal speach "Domo arigatou gozaimasu" is used. In Japan you need to care about when to switch between being informal and formal. People may misunderstand your meaning of it if you say it the wrong way.
Arubaito - "baito" for short, means part time or casual work, usually by students or other young people who can't or won't work at a 'real' or full time job. Comes from the German word "Arbeit" (:work).
Asoko - It means "there", "over there", "that place", and is used to refer to a place or position which is considered far from both sides of the speech. In a very informal sense it also sometimes could mean "genitals","sex organs".
Atashi - Informaly used by female speakers to emphasize their femininity. Being "boku" the equivalent for male!