Nearly all languages spoken on this planet feature idioms and proverbs and Japanese is no exception. In fact, the Japanese languages contains thousands of metaphors and old sayings (諺), way too much to list them all up. 
We looked around and made up a list of 10 for you to get a glimpse of Japanese proverbs. 

1. 雲泥の差
Reading: うんでいのさ (undei no sa)

Translation: “the separation between clouds and mud”

Meaning: A vast difference between two things.
2. 犬猿の仲
Reading: けんえんのなか (ken’en no naka)

Translation: “the relationship of dogs and monkeys”

Meaning: A relationship of mutual hatred. Natural enemies.
3. 為せば成る
Reading: なせばなる (naseba naru)

(Literal) Translation: “if you take action, it will become”

Meaning: You can do it if you try.
4. 青天の霹靂
Reading: せいてんのへきれき (seiten no hekireki)

Translation: A bolt (lit. thunder) out of the blue (sky).
5. 鴨が葱をしょって来る
Reading: かもがねぎをしょってくる (kamo ga negi o shotte kuru)

Translation: “a duck comes along carrying a leek on its back”

Meaning: A very convenient happening, a stroke of luck.

Explanation: The reason for this proverb is that duck soup is made with leek, so it’s as though the duck came along just asking you to eat it.

Note: This proverb has a short form for everyday usage, 鴨ネギ (kamonegi)
6. 忙中閑あり
Reading: ぼうちゅうかんあり (bouchuu kan ari)

Meaning: Even when you’re very busy, there’s occasionally time to take a rest.
7. 初心忘るべからず
Reading: しょしんわするべからず (shoshin wasuru bekarazu)

Translation: We should not forget our beginner’s spirit. (the excitement/humility of starting something new)
8. 長所は短所
Reading: ちょうしょはたんしょ (chousho wa tansho)

Translation: “our strong points are our weak points”

Meaning: Over-reliance on our strengths leads to make careless mistakes.
9. 起きて半畳，寝て一畳
Reading: おきてはんじょう、ねていちじょう (okite hanjou, nete ichijou)

Translation: “(man needs just) half a tatami mat when awake, one tatami mat when asleep.”

Meaning: You need not be rich to live a satisfied life.
10. 猫の首に鈴を付ける
Reading: ねこのくびにすずをつける (neko no kubi ni suzu o tsukeru)

Translation: “to put a bell around a cat’s neck”

Meaning: To discuss doing something that is nearly impossible to do.

Note: This proverb has its origin in one of Aesop’s fables.