If you cut your nails at night...

Today I will talk about a Japanese superstition.

"Yoru ni tsume wo kiru to oya no shinime ni aenai" (If you cut your nails at night, you won't be with your parents when they pass away).

Like this, it is thought that to cut your nails at night is something bad in Japan.

I will introduce two theories that are thought of as the derivation.

【Because it was dangerous】
Formerly in Japan, people cut their nails using a small knife. Furthermore, since there were no light bulbs, it was very dark at night. As a result, some cut their hands wrongly and some were dead because of the mistakes.

【Because it could bring bad luck】
By omitting "yoru ni tsume wo kiru" (to cut your nails at night), it becomes "夜爪 (yozume)," (night nails). This is associated with "世詰め (yozume)," which means "short-lived."

夜に爪を切ると

今日は日本の有名な迷信を紹介します。

「夜に爪を切ると親の死に目に会えない」

日本ではこのように、夜に爪を切ることは良くないことだとされています。

この理由として考えられている二つの説を紹介します。

【危険だったから】
かつての日本では、小刀で爪を切っていました。さらに、電球が無く、夜はろうそくなどが用いられたため、とても暗かったです。その結果、間違って手を切ってしまい、それが原因で死んでしまったことがあったそうです。

【縁起が悪いから】
「夜に爪を切る」を省略すると、「夜爪」となり、これは「世詰め」を連想させます。「世詰め」は「短命」を意味します。

• If you cut your nails at night...
• This sentence is perfect! No correction needed!

• Today I will talk about a Japanese superstition.
• This sentence is perfect! No correction needed!

• "Yoru ni tsume wo kiru to oya no shinime ni aenai" (If you cut your nails at night, you won't be with your parents when they pass away).
• This sentence is perfect! No correction needed!

• Like this, it is thought that to cut your nails at night is something bad in Japan.
• Like this, It is thought that to cut your nails at night is something bad in Japan.

• I will introduce two theories that are thought of as the derivation.
• I will introduce two theories that are thought of as the derivation. （Or "I will introduce two theories from which the superstition may be derived.")

• 【Because it was dangerous】
• This sentence is perfect! No correction needed!

• Formerly in Japan, people cut their nails using a small knife.
• This sentence is perfect! No correction needed!

• Furthermore, since there were no light bulbs, it was very dark at night.
• This sentence is perfect! No correction needed!

• As a result, some cut their hands wrongly and some were dead because of the mistakes.
• As a result, some cut their hands wrongly and some were dead died because of the mistakes.

• 【Because it could bring bad luck】
• This sentence is perfect! No correction needed!

• By omitting "yoru ni tsume wo kiru" (to cut your nails at night), it becomes "夜爪 (yozume)," (night nails).
• This sentence is perfect! No correction needed!

• This is associated with "世詰め (yozume)," which means "short-lived."
• This sentence is perfect! No correction needed!

• Today I will talk about a Japanese superstition.
• This sentence is perfect! No correction needed!

• "Yoru ni tsume wo kiru to oya no shinime ni aenai" (If you cut your nails at night, you won't be with your parents when they pass away).
• "Yoru ni tsume wo kiru to oya no shinime ni aenai" (If you cut your nails at night, you won't be with your parents when they pass away.)

  Complete sentence = Period should be inside parentheses
  
  http://www.turnerink.co.uk/punctuation-tips/full-stops-inside-or-outside-of-brackets/

• If you cut your nails at night...
• This sentence is perfect! No correction needed!

• Today I will talk about a Japanese superstition.
• This sentence is perfect! No correction needed!

• "Yoru ni tsume wo kiru to oya no shinime ni aenai" (If you cut your nails at night, you won't be with your parents when they pass away).
• This sentence is perfect! No correction needed!

• Like this, it is thought that to cut your nails at night is something bad in Japan.
• This Japanese saying implies that to cut your nails at night is something bad.

• I will introduce two theories that are thought of as the derivation.
• I will introduce two theories that could explain this superstition.

• 【Because it was dangerous】
• This sentence is perfect! No correction needed!

• Formerly in Japan, people cut their nails using a small knife.
• Formerly in Japan, people used to cut their nails using a small knife.

• Furthermore, since there were no light bulbs, it was very dark at night.
• This sentence is perfect! No correction needed!

• As a result, some cut their hands wrongly and some were dead because of the mistakes.
• As a result, some people cut their hands and some died because of their cut.

• 【Because it could bring bad luck】
• This sentence is perfect! No correction needed!

• By omitting "yoru ni tsume wo kiru" (to cut your nails at night), it becomes "夜爪 (yozume)," (night nails).
• This sentence is perfect! No correction needed!

• This is associated with "世詰め (yozume)," which means "short-lived."
• This sentence is perfect! No correction needed!