昨日 Sakubi: Yesterday's Grammar Guide

Lesson 12: Irregular verbs and basic formality

Now that we've covered the most common verb stems, we can cover the irregular verbs. Japanese only has two blatant irregular verbs, but they're very common. Their conjugations are completely irregular.

する, meaning "do"

来る くる, meaning "come"

する した しない せよ

くる　きた　こない　こい

The irregular imperatives are so irregular that casual spoken japanese sometimes uses completely different imperatives altogether. They're not formally correct, but you'll run into them anyway.

しろ・くれ

Many more verbs have one or two irregular conjugations, but する and くる take the cake and are the most important to know about for reading.

Let's cover basic formality while we're at it. Basic polite verbs use an auxiliary verb, ます, attached to a stem. For one-form verbs, ます attaches to the One True Base. For five-form verbs, change the u to an i, then attach ます.

食べます (Someone) eats/will eat.

行きますよ I'm heading out!

切ります Cuts [something] (polite)

Warning: don't attach ます to です, it doesn't work.

In lesson 8, we mentioned that the five-form past tense comes from this "i" stem. That version is "reduced". Let's review.

死んだ　shi n da

死にます　shi ni ma su

殺した　koro sh ta

殺します　koro shi ma su

Notice that the "i" is not pronounced in 殺した. You can pronounce it, but it'll sound weird. 死んだ removes the "i" completely, even in spelling. Also, the ん in 死んだ causes the た to become "voiced", た to だ, the same thing that turned にて into で.

Here's a comparison between the past tense and ます form of each type of five-form verb. Don't memorize this.

And these are the basic conjugations of ます.

死にます　死にました　死にません　死にませんでした

ません doesn't have a past tense of its own. To use the past tense with ません, you attach でした, the past tense of です.