Japanese conjugation, like the conjugation of verbs of many other languages, allows verbs to be morphologically modified to change their meaning or grammatical function. In Japanese, the beginning of a word (the stem) is preserved during conjugation, while the ending of the word is altered in some way to change the meaning (this is the inflectional suffix). Japanese verb conjugations are independent of person, number and gender (they do not depend on whether the subject is I, you, he, she, we, etc.); the conjugated forms can express meanings such as negation, present and past tense, volition, passive voice, causation, imperative and conditional mood, and ability. There are also special forms for conjunction with other verbs, and for combination with particles for additional meanings.
Japanese verbs have agglutinating properties: some of the conjugated forms are themselves conjugable verbs (or i-adjectives), which can result in several suffixes being strung together in a single verb form to express a combination of meanings.
Conjugable words (verbs, i‑adjectives, and na‑adjectives) are traditionally considered to have six possible conjugational stems or bases (活用形, katsuyōkei; literally "conjugation forms"). This article lists those from the negative base (未然形, mizenkei), as well as the tentative base (推量形/意思形, suiryōkei/ishikei) that was split off during the post‑WWII spelling reforms.
The passive or passive potential turns the patient (or target) or victim of an action into a subject, which can be marked with the nominative particle ga.
The pure passive simply expresses what act is done by the agent (A) to the patient (P), thus A ga P o yobu (AがPを呼ぶ; 'A calls P') becomes P ga A ni yobareru (PがAに呼ばれる; 'P is called by A'). The agent is typically marked with ni, but kara can sometimes be used instead, especially if ni might be ambiguous; for example in P ga A ni B ni shōkai sareru (PがAにBに紹介される), it is not clear which between A and B the agent is, so kara can be used instead as in P ga A kara B ni shōkai sareru (PがAからBに紹介される; 'P is introduced by A to B').
The adversative, "victimizing" or affective passive expresses how a victim (V) is affected by, or suffers from, if the original verb is intransitive, the act being done by an agent, as in V ga A ni shinareru (VがAに死なれる; 'V suffers because A dies'); or, if the original verb is transitive, the act being done by an agent to a patient, as in V ga A ni P o yobareru (VがAにPを呼ばれる; 'V suffers because A calls P'). The terms adversative and victimizing are broadly correct, although the "victim" can sometimes be positively or even desirably affected by the action, so affective would be a more general term; for example, Atsui kara soto ni dete kaze ni fukarete kimasu (暑いから外に出て風に吹かれてきます; transl. It's hot so I'll go outside and get some wind, lit. 'It's hot, so I'll go outside and get affected by the wind blowing'), Sensei ni kodomo o homerareta (先生に子供を褒められた; transl. My kid was praised by her teacher, lit. 'I was affected by the fact that the teacher praised my kid'), etc. Sometimes what seems to be positive may turn out to be negative with additional context, such as Itsu datta ka, watashi wa densha no naka de seinen kara seki o yuzurareta koto ga atta […] Watashi wa sono toki, isasaka yūutsu de atta (いつだったか、私は電車の中で青年から席を譲られたことがあった[…]私はその時、いささか憂鬱であった; transl. Once on a train I was given a seat by a young man […] I was a bit depressed that time [because I would rather him ignore my disability and treat me like a normal person]). English has some similar constructions with intransitive verbs, though not necessarily with a negative connotation, such as "I got rained on" or "I got talked to".
The passive can also have no passive meaning, but is merely a more honorific way to exalt the subject. Some verbs that come with the particle ni may be ambiguous when used this way, as it might not be clear whether it is in the passive or the honorific without context. For example, since the verb katsu (勝つ; 'win') comes with ni whether or not it is in the passive, in the line "Anata ga hime ni kataretara chin mo kōfuku de gozaimasu zo" (「王子殿が姬に勝たれたら朕も幸福で御座いますぞ」), out of context, the king could be glad either if the prince is defeated by his princess (affective passive), or if he defeats her (subject exaltation); in context, it is the subject‑exalting interpretation, hence "We would be delighted if ye defeat our princess."
Actual sentences may lack one of the said components (P, V or A) and therefore can become ambiguous (purely passive, adversatively passive or honorific) without additional context, for example kekkonshiki ni yobareru (結婚式に呼ばれる; 'one gets invited to weddings; one suffers because someone else's invited to weddings; those honoroble invite others to weddings'). Intransitive verbs, such as korareru (来られる) and arareru (あられる), do not have the pure passive meaning, only the other two, as in V ga A ni korareru (VがAに来られる; 'V suffers because A comes') and S ga C de arareru (SがCであられる; 'S is (honorably) C').
Historically, the "passive" construction has also had potential use, but except for ichidan verbs and kuru, this use now has a dialectal or old‑fashioned literary flavor. It has been argued that the various meanings of the passive arose from the spontaneous potential (see #Potential for more), which spawned both the regular potential and the regular passive, the latter of which came to be used additionally for subject exaltation. It has also been suggested that the pure passive came to be in its current state due to translations from the English passive.
