Meaning
The kanji 再 (さい) primarily means "again," "a second time," or "re-." It signifies repetition, recurrence, or doing something anew. You'll find it incredibly common in daily Japanese vocabulary because it expresses actions that happen more than once. Often, it acts as a powerful prefix in compound words, indicating that an action or state is being revisited or re-initiated.
While not a simple pictograph, the kanji's etymological origin is generally considered an ideograph. It visually represents a repeated action or state. Ancient forms might have depicted an object passing through a gate or barrier multiple times, or a pattern being drawn repeatedly. The modern form of 再 has two main visual elements: the top part resembles 一 (いち, ichi), meaning "one" or "first," and the bottom part, 冂 (けいがまえ, kei-gamae), signifies an enclosure or boundary. Some interpretations suggest the "one" could mark an action, with the enclosure implying a return to a starting point or a cycle repeated within a defined space. Ultimately, it conveys a strong sense of returning to a previous state or re-executing an action.
With just 6 strokes, 再 is relatively easy to write and remember. Japanese students learn it in the 4th grade, highlighting its foundational importance in the language curriculum. Its clear meaning and simple visual structure make it a key building block for learners to understand concepts of repetition and recurrence.
Readings
On'yomi (音読み) — Chinese-derived readings
The On'yomi (音読み), or Chinese-derived reading, for 再 is サイ (SAI). This is by far the most common way to pronounce 再, especially when it appears as part of a compound word. You'll encounter サイ in many formal or compound contexts where the meaning of "again," "re-," or "second time" is conveyed. It often acts as a prefix to a verb or noun kanji in terms related to repetition, re-doing, re-establishment, or re-examination.
再開 (saikai) — reopening, resuming (e.g., a shop reopening after renovation)
再生 (saisei) — regeneration, reproduction, recycling (e.g., recycling paper, cell regeneration)
再会 (saikai) — meeting again, reunion (e.g., a reunion with old friends)
Kun'yomi (訓読み) — Native Japanese readings
The Kun'yomi (訓読み), or native Japanese reading, for 再 is ふたたび (futatabi). This reading appears when 再 stands alone, often as an adverb meaning "again" or "a second time." It carries a slightly more literary or formal feel than simply saying また (mata), though both express similar ideas of repetition. ふたたび can modify verbs or entire clauses, emphasizing the 'second' instance of an action.
再 (futatabi) — again, a second time (e.g., to try again)
再訪れる (futatabi otozureru) — to visit again (e.g., to visit a place for a second time)
再現れる (futatabi arawareru) — to reappear (e.g., a person or phenomenon reappearing)
Common Words & Compounds
The kanji 再 is incredibly versatile, appearing in many essential Japanese vocabulary words. It often serves as a prefix, adding the meaning of "re-" or "again" to a base kanji. Learning these compounds will greatly enhance your understanding of Japanese expressions related to repetition and renewal.
Actions & Events Related to Repetition
再開 (saikai) — reopening, resuming (e.g., a store reopening, a meeting resuming after a break)
再発 (saihatsu) — recurrence, relapse (e.g., a disease recurring, a problem resurfacing)
再考 (saikō) — reconsideration, rethinking (e.g., re-evaluating a plan or decision)
再建 (saiken) — reconstruction, rebuilding (e.g., rebuilding a house after a disaster)
再燃 (sainen) — re-ignition, rekindling (e.g., an old flame rekindling, a fire reigniting)
Processes & States of Renewal
再生 (saisei) — regeneration, reproduction, recycling (e.g., cell regeneration, recycling waste materials)
再現 (saigen) — reproduction, reappearance, reconstruction (e.g., recreating a historical scene or event)
再認識 (saininshiki) — re-recognition, reappreciation (e.g., re-evaluating one's understanding or perception)
再利用 (sairiyō) — reuse, recycling (e.g., reusing plastic bottles or bags)
再就職 (saishūshoku) — re-employment, finding a new job after being unemployed
Grasping these compounds is key to expanding your Japanese vocabulary, as 再 acts as a fundamental building block for countless everyday and specialized terms. Because its meaning of "re-" or "again" is so consistent, you'll often find it intuitive to predict the meaning of new compounds once you understand the kanji it's paired with.
Example Sentences
来週再度会いましょう。
Raishū saido aimashō.
Let's meet again next week.
彼は再日本へ行くことを決めた。
Kare wa futatabi Nihon e iku koto o kimeta.
He decided to go to Japan again.
古い本を再生して紙を作る。
Furui hon o saisei shite kami o tsukuru.
We recycle old books to make paper.
店は来月から再開する予定だ。
Mise wa raigetsu kara saikai suru yotei da.
The store is scheduled to reopen from next month.
彼らの再会は感動的だった。
Karera no saikai wa kandōteki datta.
Their reunion was touching.
問題が再発しないように対策が必要だ。
Mondai ga saihatsu shinai yō ni taisaku ga hitsuyō da.
Measures are needed to prevent the problem from recurring.
この計画は再考の余地がある。
Kono keikaku wa saikō no yochi ga aru.
There is room for reconsideration of this plan.
再の挑戦で彼は成功した。
Futatabi no chōsen de kare wa seikō shita.
He succeeded on his second attempt.
Memory Tip
To remember 再 ('again,' 'a second time'), try visualizing its components in a story. The kanji appears to combine 一 (いち, ichi), meaning "one" or "first," with 冂 (けいがまえ, kei-gamae), an enclosure or boundary. Imagine someone trying to jump over a fence (冂) for the first time (一). If they don't succeed, they'll have to try 'again'! Alternatively, picture a character writing the number 'one' (一) inside a box (冂), only to make a mistake and have to do it 'again.' You might also see the top part as a stylized 二 (に, ni), meaning 'two,' which directly suggests the 'second' time or 'again.' By linking the idea of an initial attempt (一) with a repetition or re-entry into a situation (冂), you can firmly associate 再 with 'again' or 'a second time.'