The Japanese verb system is at once the simplest and most complicated out of all the languages I've seen (except maybe the Bantu languages). Japanese verbs are extremely regular in their conjugation and in their representation in writing. Not only that, but the verb always comes at the end of the sentence.

For discussing verbs or presenting them in a dictionary, a Japanese verb is used in its "dictionary form". This form always ends in -u. It is important for Westerners to note that this so-called "dictionary form" is not the infinitive form. The dictionary form is actually the simple present tense form. We say "to eat" in English and "manger" in French, but the Japanese taberu actually means just "eat", with no "to" attached.

Japanese verbs can be grouped into three classifications:

Verbs are classified according to their endings, as described below. For Westerners, especially English or French speakers, it's nice to know that the "irregular" class contains only two verbs, and they are regular unto themselves. As far as the other two groups, the verbs are divided up by their endings as follows.

Ichidan verbs are those that end in -iru or -eru. Some examples:

The rest of the verbs are called Godan verbs. They end in anything else. Of minor confusion to novices is the fact that some verbs look like Ichidan verbs in their dictionary forms, because they end in -iru or -eru, but are actually Godan verbs ending in -ru. Some examples:

As you can imagine, there are many more Godan verbs than there are Ichidan verbs. The last three verbs in that list are examples of Fake Ichidan verbs -- like I said, they are Godan verbs with the -ru consonant ending. They are not irregular verbs.

There are exactly two irregular verbs in Japanese. These are suru (do) and kuru (come). The thing that makes them irregular is that they don't always use the same stem for each base, whereas all other verbs have only one stem (more on stems and bases below). There are several verbs, such as iku, that have some slight inconsistencies in certain bases (itte and itta in Base 6 and Base 7, respectively). Furthermore, several very old verbs, such as the so-called "honorific" verbs, are something of a law unto themselves. No set of rules can completely explain how to speak a language -- actual usage is always the final authority.

Also, special rules apply to the verbs desu, iru, aru, and oru. Desu is the copula, and like all other copulas in all other languages, it is "irregular". Aru becomes nai in the plain present negative, for reasons which make some sense in light of verb endings that incorporate it.

As far as conjugating Japanese verbs, it is a less complex process than it is in English, French, or German, depending on how you look at it. Conjugation here relies much more on formula and mechanics than it does on memory or instinct. To conjugate a verb, you take the "stem" of the verb, add the "base", and then affix an "ending" if necessary (and most of the time it is). There are essentially 7 bases that I know of, and each base generally allows for several types of endings. This system is one of the reasons that Japanese is so different from Western languages -- the elements of meaning that in English are usually conveyed with linking verbs and complex predicates are instead encapsulated directly into the Japanese verb.

It is difficult to describe Japanese verbs in terms of "tenses" as is usual in discussing English, French, etc. There are either two tenses or a million tenses, depending on how you consider it. It is worth noting, however, that while there are counterparts to the English "past" and "present" tenses in Japanese, there is no "future" tense or indication. The present tense is used instead.

To get the stem of a Japanese verb, you remove the last syllable of the dictionary form:

You need to remember what the removed syllable was, however, because it influences later steps.

You then add the appropriate base. For our examples, let's form the polite present (the famous "desu-masu" form). This is one of the most useful forms for travellers or businessmen. The polite present requires base 2, which is formed for Godan verbs by changing the u in the removed syllable to i and adding it back on, with appropriate phonetic changes. For Ichidan verbs, nothing is added.

  • tabe
  • kaki
  • mi
  • hanashi
Then, we add the ending, which in this case is -masu.
  • tabemasu
  • kakimasu
  • mimasu
  • hanashimasu
These are the polite present forms, ready to be used in a sentence:

Asa-gohan o tabemasu ka.
Are you going to eat breakfast?

Watashi wa tegami o kakimasu.
I'm writing a letter.

Ichi-ji-kan terebi o mimasu.
I'm going to watch TV for an hour.

Nihon-go o hanashimasu ka.
Do you speak Japanese?
Note: these translations are not literal.

A zillion other endings are possible. For example, to express potential (can/cannot), you use Base 4 with the ending -ru. To form Base 4, you change the u in the removed syllable into e for the Godan verbs; for the Ichidan verbs you remove the "-ru" and add "rareru" instead. For the same verbs, we get:

  • taberareru
  • kakeru
  • mirareru
  • hanaseru
Note that we have created four new Ichidan verbs, which themselves must be conjugated again:

Taberaremasu ka.
Can you eat?

Tegami o kakemasu ka.
Can you write a letter?

Hanasemasen yo.
I cannot speak.

All this isn't as complicated as it sounds, but it takes some getting used to. Most of the endings are predictable once you have some knowledge of the language, and forming the bases properly becomes second nature after awhile. A major stumbling block for initiates is the fact that so-called "endings" are sometimes verbs themselves, or result in new verbs, like the above.

As a parting shot, I'll drag to the altar for sacrifice one of the longest Japanese verbs I can think of off the top of my head. To express that an action was done suddenly, you use the ending "-dasu" with Base 2. Sounds simple enough. In our example, we're talking about a child who suddenly ran off towards his house.

We begin with the verb for run, hashiru. The stem is hashi-. So far, so good.

Next, we form Base 2. However, hashiru is one of those pesky verbs that looks like it's Ichidan but is actually Godan. How could I tell? I can't, you just have to know what they are. Therefore, Base 2 for hashiri is not hashi- but hashiri-.

We then add the required ending, -dasu, which, with verbs in Base 2, indicates sudden action. However, dasu is itself a verb. So we have to conjugate it into the polite past form:

dasu --> dashi- --> dashimashita

The complete verb is, therefore, hashiridashimashita. Using it in the sentence:

Kodomo wa uchi no hoo ni hashiridashimashita.
The child suddenly ran in the direction of the house.

Of course, it doesn't stop there. There are innumerable endings, many of which are idiomatic, and then there are a whole set of "informal endings" which draw on all 7 bases and are used a lot in casual speech. If you think this is hard, though, try English, which has no concept of regular or irregular verbs at all (there are some 250 "verb classes" where verbs in a particular class tend to behave the same way) plus infamous subjunctives and idiomatic uses of linking verbs.