Ichidan

Ichidan — one of the two main Japanese verb conjugation classes (一段動詞, ‘one-row verbs’) — characterised by a simpler conjugation pattern where the final -ru is dropped before adding suffixes.

Definition

One of the two main Japanese verb conjugation classes (一段動詞, ‘one-row verbs’) — characterised by a simpler conjugation pattern where the final -ru is dropped before adding suffixes.

In Depth

One of the two main Japanese verb conjugation classes (一段動詞, ‘one-row verbs’) — characterised by a simpler conjugation pattern where the final -ru is dropped before adding suffixes.

In-Depth Explanation

Ichidan (一段, “one-row”) is the grammatical term for one of the two primary Japanese verb conjugation classes. The name refers to the single vowel row used in conjugation — unlike godan (“five-row”) verbs, ichidan verbs use only one vowel position (the -e or -i row) when combining with suffixes. In teaching contexts and reference works, ichidan verbs are also called Group II verbs or, in machine-readable dictionaries (JMdict), tagged as v1.

Core characteristics:

• All ichidan verbs end in -る (-ru) in dictionary (plain, non-past) form
• The stem — everything before the final -る — never changes vowel during conjugation
• Conjugation consists of: remove -る + add suffix
• All ichidan stems end in either -e or -i (hence “eru verbs” and “iru verbs” as informal categories)

Relationship to ichidan-verb:

The entries ichidan and ichidan verb are closely related. “Ichidan” is the grammatical category label (a noun in Japanese grammar terminology, often used adjectivally: 一段動詞 = “ichidan verb”). The key facts about conjugation, the -ru identification problem, and the paradigm are treated in the ichidan verb entry. This entry addresses the typological and pedagogical framing of the category.

Contrast with godan:

Pedagogical framing:

In contemporary Japanese L2 pedagogy, ichidan verbs are often introduced as the “simpler” class — the uniformity of “drop -ru, add suffix” is presented as an advantage. However, this simplicity is complicated by the -ru identification problem: ichidan and many godan verbs share the -ru surface ending in dictionary form, making class identification an ongoing challenge beyond the basic pattern.

The “ru-verb” label:

Informal learner vocabulary often calls ichidan verbs “ru-verbs” and godan verbs “u-verbs” — a simplified but imprecise alternate terminology:

• “Ru-verbs” (ichidan): ends in -ru; drop -ru to conjugate ✓
• “U-verbs” (godan): ends in vowel+u; but many ending in -ru fall here ✗

The “ru-verb / u-verb” shorthand is useful pedagogically for beginners but creates the logical problem that some “u-verbs” (godan) also end in -ru.

History

The ichidan/godan classification is rooted in classical Japanese grammar (koten bunpō) taxonomy. Classical Japanese had a more complex system including kami-ichidan (“upper one-row”) and shimo-ichidan (“lower one-row”) verb types, distinguished by the vowel row (i-row vs. e-row) of their stem. Modern Japanese merged these into the single ichidan category as the distinction became neutralised in spoken language during the Edo period. The simplified modern ichidan/godan binary was codified in Meiji-era school grammar (gakkō bunpō) and remains standard in L1 education and L2 teaching.

Common Misconceptions

• “Ichidan is the ‘easy’ verb class.” While the conjugation pattern itself is simpler, the identification difficulty — knowing which -ru ending verbs are ichidan and which are godan — makes ichidan classification a persistent source of errors for learners at intermediate and even advanced levels.
• “‘Ru-verb’ is the same as ichidan.” The “ru-verb” label is a learner shorthand that works in most but not all cases. Several very common verbs (帰る, 切る, 走る, 入る) are -ru ending godan verbs, making the “ru-verb = ichidan” equation unreliable.
• “You can always hear which class a verb is in.” Phonological cues (the vowel preceding -ru) are often proposed as identification aids, but exceptions are too numerous and semantically important to rely on in practice.

Social Media Sentiment

Ichidan/godan content is foundational in Japanese language learning resources. Introductory YouTube videos, blog explainers, and grammar textbook sections all begin with this classification system. Among intermediate learners, the -ru identification problem persists — HiNative and r/LearnJapanese regularly receive questions about specific misidentified verbs. The terms “ichidan,” “godan,” “Group I / II,” “ru-verb / u-verb,” and “v1 / v5” appear in different learner communities reflecting different resource backgrounds.

Last updated: 2026-04

Practical Application

• Learn class with the word: When adding any Japanese verb to your vocabulary study, always learn its class alongside its meaning and reading. Resources like Jisho.org mark this clearly (v1 = ichidan).
• Identify the problem verbs early: Prioritise learning the most common godan -ru verbs (帰る, 切る, 入る, 走る, 知る, 分かる, 作る, 喋る) explicitly so these don’t default to incorrect ichidan conjugation patterns.
• Te-form as a class detector: The te-form is one place where class becomes unavoidably visible. If a -ru verb has a te-form of -って (e.g., 帰って kaette), it is godan; if -て without consonant duplication (食べて tabete, 見て mite), it is ichidan.

Related Terms

• Godan
• Ichidan Verb
• Verb Conjugation
• Te-form
• Japanese Grammar

See Also

Sakubo – Japanese App

Sources

• Makino, S., & Tsutsui, M. (1986). A Dictionary of Basic Japanese Grammar. Japan Times. Standard pedagogical reference with complete conjugation tables for ichidan and godan verbs; foundational for L2 learners approaching verb classification.
• Shibatani, M. (1990). The Languages of Japan. Cambridge University Press. Comprehensive linguistic analysis including the historical origins of ichidan and its relationship to classical Japanese verb classes.
• Vance, T. J. (2008). The Sounds of Japanese. Cambridge University Press. Covers phonological dimensions of Japanese verb morphology relevant to understanding the vowel-row logic underlying the ichidan classification.