One of the first things new learners of Japanese must struggle with is the amazing variety of classifiers for numbers. When counting books, for instance, the number is followed by 冊 (satsu, volumes, as in issatsu, nisatsu etc.); for thin, elongated objects such as pencils it’s 本 (hon, as in ippon, nihon, sanbon, etc.); for pieces of paper like tickets it’s 枚 (mai); for à la carte orders of sushi it’s 貫 (kan); for pairs of shoes it’s 足 (soku); and so on.
There’s no generic counter that will cover everything, but in a pinch you can resort to the classifier 個 (ko), as in 一個 (ikko, one piece). In daily speech, 個人 (kojin) means an individual, and is heard in situations like 個人的に何の関係もないです (Kojinteki ni nan no kankei mo nai desu, I have no personal contact with [him] at all). You may recognize the sign 個人 (kojin) atop some taxis, which indicates an owner-driver.
For translators like yours truly, numbers present little difficulty. What’s harder to deal with are Japanese suffixes, which don’t always neatly mesh with English equivalents.
Take 系 (kei), which is often used to indicate relationship to some group. Both in the natural sciences and in engineering, kei is typically rendered as “system.” For example there’s 生態系 (seitai-kei, ecosystem) and 太陽系 (taiyō-kei, solar system).
Kei often finds its way into general or generic descriptions without going into detail. One might, for instance, say about a person’s job, 彼は外資系企業に勤めている (Kare wa gaishikei kigyō ni tsutomete iru, He’s employed by the Japanese subsidiary of a foreign firm).
The kei suffix is frequently used to describe members of ethnic or religious groups. In media reports, I often see an Asian person of indeterminate nationality being described thusly: 事故でアジア系外国人が重傷を負いました (Jiko de ajia-kei gaikokujin ga jūshō wo oimashita, A foreigner of Asian origin was seriously injured in the accident). The 日系人 (nikkeijin) are people with Japanese ancestry, such as 日系米人 (nikkei beijin, Japanese-Americans).
Use of kei can be usefully vague — for instance, saying コーエンさんはユダヤ系アメリカ人です (Kōen-san wa yudaya-kei amerikajin desu) describes Mr. Cohen as being from a Jewish-American background, without necessarily identifying him as ユダヤ教徒 (yudayakyōto, a practitioner of Judaism).
A word that appears fairly frequently in crime-related news articles is 出会い系サイト (deai-kei saito), used to refer to online dating or encounter sites on the Internet. Here, kei functions to classify the type of site, and need not be translated.
Another commonly used suffix is the character 的 (teki), originally referring to a target, which is why it’s found in words like 目的 (mokuteki, objective), 目的地 (mokutekichi, destination) and 的確 (tekikaku, precise or accurate). It’s often heard in expressions like 一般的に言う (ippanteki ni iu, generally speaking), and pops up in such frequently used words as 積極的 (sekkyokuteki, assertive or positive) and 消極的 (shōkyokuteki, negative or pessimistic).
Then there’s the suffix 性 sei, using the risshin-ben (heart classifier on the left) combined with 生 (sei or shō, life or to give birth).
Sei means the nature of things, and can pop up almost anywhere. Take 可能性 (kanōsei, possibility), 必要性 (hitsuyōsei, necessity) or 多様性 (tayōsei, “many-types-nature,” or diversity). A disease may be described as 流行性 (ryūkōsei, “flowing-going nature,” i.e., epidemic).
The character for sei has two alternate readings. When two people don’t get along, they are said to be 相性が悪い (aishō ga warui, “mutual nature is bad,” i.e., incompatible). Another reading can be found in 根性 (konjō, “root-nature,” i.e., stubborn or tenacious).
But sei is the most common reading and it finds particularly wide use in scientific and medical fields. Some are pretty straightforward, like (放射性 hōshasei “release-shoot nature,” i.e., radioactive) and 特性 (tokusei, special characteristic). Other frequently seen medical terms include 慢性 (mansei, “slow nature,” i.e. chronic); 急性 (kyūsei, “hurried nature,” i.e., acute); and 悪性 (akusei, “bad nature,” i.e., malignant).
I wear eyeglasses to correct 近視 (kinshi, myopia or nearsightedness), which is 先天性 (senten-sei, “previous-heaven nature,” i.e., hereditary). It would appear that ten refers not to the Judeo-Christian concept of heaven, but to svarga, a heaven-like Buddhist realm that’s visited at stages of death and rebirth. Now I know why I am balding and have to squint to read fine print.
Sei also lets me flaunt my familiarity with the famous 相対性理論 (sōtaisei riron, the theory of relativity). You don’t need to be Einstein to recite it in Japanese — it’s almost the same as in English. Just say: イー・イコール・エム・シー二乗 (ii ikōru emu shii nijō). In other words, E=MC₂.