This post is a brief anticipation of some of the more important feature of the Japanese verb that are likely to be strange to you. It will probably help you to understand some of the unfamiliar constructions and features of form and meaning that must necessarily occur in the sentences that have been quoted as example.
1. Japanese verbs do not have different forms to indicate the number or person or gender of the subject of the sentence. The same form are used whether the subject is I or you or they or anything else.
2. Verb are very often used without a pronoun subject, as in the example above. In such cases you recognize the subject by context.
3. There are only two real tenses in Japanese, a present and a past. Japanese is not so much interested in the subtleties of time as is English. There is no true future tense; the present is used to express definite future ideas.
東京へ行きました。(Past tense) Tokyo he iki mashita. : I went to Tokyo.
東京へ行きます。(Present tense) Tokyo he iki masu. : I go to Tokyo. I shall go to Tokyo.
4. Although tenses are few, Japanese is extremely rich in verb forms that indicate moods or aspects of likeness, or belief on the part of the speaker, or appearances. Most of these are beyond the scope of manual. Japanese learner often asks me about this. I need to answer case by case. I need to understand more as a teacher. For example,
彼は帰るでしょう。 kare ha kaeru desho, might be translated
‘He is probably returning.’ ‘He will probably return’ ‘I think he will return’
5. There are several compound verb forms that are frequency used. There is a progressive aspect that corresponds surprisingly closely to the English from in meaning and formation. It is made with a participle and a conjugated form of a verb meaning ‘to be’
何をしていますか？ Nani wo shite imasuka? : What is he doing?
6. Each Japanese verb has an entire negative conjugation to balance its possible form. Unlike English, where you simply add no or not to most sentence to make negative, Japanese has completely different verb form to indicate a negative idea.
本を買った （polite 本を買いました）。 Hon wo kaltuta (Hon wo kai mashita) ; I bought a book.
本を買わなかった (polite 本を買いませんでした ) Hon wo kawanakaltuta (Hon wo kaimasendeshita) : I did not buy a book.
7, You will observe that two versions of the same idea have been given in the sentence above. Each verb has two sets of form,
(a) Its true forms made by conjugating the verb itself.
(b) Courtesy form that are made by using a stem of the verb, and adding to it various forms of an ending whose stem is ‘masu’.
8. Japanese verbs are highly regular. There are only two really irregular verbs in the language, and these are only irregular only in their stems. There are perhaps a half dozen other common verbs that are very slightly irregular in one or two forms. As a result, even though there are more forms per verb thatn there are in English, and the endings used to make particular forms are longer than English endings, the Japanese verb is really very simple, Verbs are so completely regular in the way they make their forms that you will be astonished at the ease with which you will master them.
These are mainly from the textbook ‘Basic Japanese grammar’.