Japanese Verbs Polite Form Negative: ~ ません (masen)

Now that we're familiar with plain/dictionary ~u (う) form, polite ~ ます(masu) and Plain Form Negative: ~ ない (nai), let's try ~ません (masen), which is the negative of polite ~ます form.

Adding ~ません is no diffeent from adding ~ます. If you master polite form, simply change ~masu to ~masen. If not clear, read below:

Group 1: ~ U ending verbs (godan) plain negative form:

• To make negative ません form out of Type 1 verbs (godan), ~u ending to ~i and add masen: verb~u ---> verb~i+masen (plain form ---> present polite negative form)
• when making a negative form for the verb ending in ~つ(tsu) change it to ち(chi) first:　matsu （待つ） ---> ma~chi ---> machimasen （待ちません）
• when making a polite form for the verb ending in ~す(su) change it to し(chi) first: kasu （貸す） ---> ka~shi ---> kashimasen （貸しません）

Watashi wa kasa o kaimasen. (I'm not going to buy an umbrella.)
Kare wa machimasen. (He won't wait.)
Kimiko wa Osaka ni ikimasen. (Kimiko isn't going to Osaka.)

And here are some ichidan:

Group 2: ~ Iru and ~ Eru ending verbs:

• Change ichidan (~Iru and ~Eru) verbs by dropping the ~ru at the end and adding ~masen.

~ Iru ending verbs

kiru （着る） kimasen - not going to wear
miru （見る） mimasen - not going to see
okiru （起きる） okimasen - not going to get up
oriru （降りる） orimasen - not going to get off
shinjiru （信じる） shinjimasen - not going to believe

~ Eru ending verbs

akeru （開ける） akemasen - not going to open
ageru （あげる） agemasen - not going to give
deru （出る） demasen - not going to go out
neru （寝る） nemasen - not going to sleep
taberu （食べる） tabemasen - not going to eat

Watashi wa ima tabemasen. (I'm not going to eat now.)
Kanojo wa kasa o karimasen. (She isn't going to borrow an umbrella.)

Group 3: Irregular Verbs くる (kuru) and ~する (~suru)

• To make ~ません form out of kuru, change kuru to kimasen
  
• To make ません form out of suru, change suru to shimasen
• To make ~ません form out of ~suru verbs, change ~suru ending to ~shimasen
  

benkyousuru （勉強する）benkyoshimasen - not going to study
ryokousuru （旅行する）ryokoushimasen - not going to travel
etc.

ARIMASEN - The polite form of DESU's opposite JA NAI

When you want to say something ISN'T, you use "ja nai" じゃない, "janai des" じゃない です . Or, If you want to be polite and formal, use ありません (arimasen):

• arimasen is a polite and formal form of nai
• formal way of ja is dewa
  

If you want to be polite but not formal, use nai desu.

You can mix them like these. Example: That's not food.

Sore wa tabemono ja nai. (informal)
Sore wa tabemono dewa nai. (written informal)
Sore wa tabemono ja nai desu. (polite, informal)
Sore wa tabemono ja arimasen. (affirmative informal, from mother to child)
Sore wa tabemono dewa arimasen. (polite, formal)

Find "dewa arimasen" below.
.

You may notice that dewa is では, not でわ!

And, I found another valid hybrid:
Sore wa tabemono dewa nai desu. (???)

This is something I don't get, please leave a comment below if you know what situations it fits. My guess it's OK between not-too-close relatives... am I right?