Grammar JLPT Level N4 - Lesson 6

Structure of そう:

Verb［ます］+ そう + だ
［い］Adjective［い］+ そう + だ
［な］Adjective + そう + だ

Negative:
Verb［ない］+ な + そう + だ
［い］Adjective ［ない］ + なさ + そう + だ
［な］Adjective + では⁽¹⁾ない + なさ + そう + だ

Exceptions:
いい￫よい + さそう + だ￫よさそうだ

⁽¹⁾ じゃ

Details about そう:

そうだ is one of the 18 primary auxiliary verbs in Japanese, and can be used in two (2) different ways. The broad meaning in each of its applications is that something 'seems' to be a certain way. Due to this, そう is regularly translated as 'seems like', 'looks like', or 'appears as though'.
In this lesson, we will focus on the form that is used with the conjunctive (stem) form of words. Please examine the structure guide to see these forms.

彼女(かのじょ)は毎日(まいにち)走(はし)りそうだ。
She seems like she runs everyday.
これは正(ただ)しそうだ。
This seems correct.
あの店員(てんいん)は丁寧(ていねい)そうだ。
That clerk seems like he is attentive.

そう

Usage Notes for そう:

そう may also be used when attached to the い-Adjective, ない. In this case, there is a unique conjugation rule which we will need to be careful of. As always, い will be removed from ない before attaching そう. However, さ will be inserted between な, and そう. This creates the expression なさそう.

彼(かれ)の部屋(へや)は汚(きたな)くなさそうだ。
His room doesn't seem messy.
あの車(くるま)は小(ちい)さくて便利(べんり)じゃなさそう。
That car is small, and looks inconvenient.

Note that this addition of さ does not happen with verbs. This is due to the ない that is used with negative verbs being an auxiliary verb, and not an い-Adjective. With the auxiliary verb ない, simply remove the い, before adding そう directly to the stem.

彼(かれ)はもうイギリスに帰(かえ)らなそうだ。
It appears that he is not going back to England.

This そう is utilized exclusively to make predictions/guesses about something based on visual information. It is relatively low confidence, so should not be used for things that are obvious. In these cases, みたい would be used instead.

明日(あした)は朝(あさ)から雨(あめ)が降(ふ)るみたいだ。
It looks like it is going to start raining tomorrow morning. (Higher confidence)
明日(あした)は朝(あさ)から雨(あめ)が降(ふ)りそうだ。
It seems like it is going to start raining tomorrow morning. (Lower confidence)