In the Japanese language, the universal past tense marker is the hiragana た (ta). This article will cover how the simple/casual past tense for a verb is formed and some examples of its usage outside of the verb's past tense will be explored.
There are three verb groups in the Japanese language, and the group in which a verb belongs will determine how it is conjugated into its simple past form. The conjugations are identical to the formation of the て form.
Group One Verb Conjugation Rules
The simple past た form's conjugation system is identical to the て form's. So to conjugate a Japanese group one verb into its respective simple past (た) form, you need to choose a specific stem change based on the verb's ending and then add the ending た.
If the verb ends with う, つ or る; replace the ending with った
If the verb ends with ぶ, む or ぬ; replace the ending with んだ
If the verb ends with く or ぐ replace the endings with いた and いだ respectively.
If the verb ends with す; replace the ending with した
買う (kau) - (to buy)
立つ (tatsu) - (to stand)
走る (hashiru) - (to run)
買った (katta) - (bought)
立った (tatta - stood)
走った (hashitta - ran)
遊ぶ (asobu) - (to play)
読む (yomu) - (to read)
死ぬ (shinu) - (to die)
遊んだ (asonda) - (played)
読んだ (yonda) - (read)
死んだ (shinda) - (died)
働く (hataraku) - (to work)
泳ぐ (oyogu) - (to swim)
話す (hanasu) - (to speak)
働いた (hataraita) - (worked)
泳いだ (oyoida) - (swam)
話した (hanashita) - (spoke)
The verb 行くis an exception to the aforementioned conjugation pattern. Rather than taking the form 行いた like a typical verb ending in く, is instead conjugated to 行った as if it ended in う つ or る.
Group Two Conjugation Rule
As with the formation of the て form and most other tenses, the simple past tense for group two verbs is formed by simply dropping the ending る.
食べる (taberu) - (to eat)
信じる (shinjiru) - (to believe)
起きる (okiru) - (to wake up)
食べた (tabeta) - (ate)
信じた - (shinjita) - (believed)
起きた (okita) - (woke)
Group Three Conjugation Rules
Group three is also simple, as it only includes the two irregular verbs する and 来る.
する (suru) - (to do)
来る (kuru) - (to come)
した (shita) - (did)
来た (kita) - (came)
On its own, the simple/casual past tense form, conveys the past tense of a verb, although it is more casual than its polite form counterpart:
先生はこの本を読んだ (sensei wa kono hon wo yonda) - (The teacher read this book)
その椅子に座った (sono isu ni suwatta) - (I sat in that chair)
When you add the suffix ほうがいい (hou ga ii) to a verb in its simple past tense form, it translates to "it would be better to do this" based on the verb in question:
ここに座ったほうがいいですよ (koko ni suwatta hou ga ii desu yo) - (It would be better to sit here you know.)
エアコンを直ぐに直したほうがいい (eakon wo sugu ni naoshita hou ga ii) - (It would be better to repair the air conditioner immediately.)
When the simple past is suffixed with the hiragana り (ri), you can create a list of actions which you may be doing now, regularly, did, or intend to do. The final verb is followed by する in this sentence pattern.
昔図書館で本を読んだり勉強したりしました (mukashi tosyokan de hon wo yondari benkyou shitari shimashita) - (In the past I read books and studied at the library.)
たら Conditional Form
The simple past tense is used as the basis for one of the Japanese conditional forms. The たら conditional form translates to an "if.. then" expression. The たら form does have additional meanings although I will not go deep into details about the conditional forms in this article:
この小説を読んだら喜びます (Kono syousetsu wo yondara yorokobimasu) - (If you read this novel you will be pleased.)