鵬程萬里 in Chinese / Japanese...

鵬程萬里 is an ancient Chinese proverb used in modern times to wish someone a long and successful career.

It's really about the 10,000 Flight of the Peng (Peng, also known as Roc is a mythical fish that can turn into a bird and take flight).

莊子
Zhuangzi or Chuang Tzu

Breaking down each character:
1. Peng or Roc (a kind of bird).
2. Journey (in this case, a flight).
3. 10,000 (Ten Thousand).
4. Li is a unit of distance often referred to as a “Chinese Mile,” though the real distance is about half a kilometer.

Direct Translation: “Peng's Journey [of] 10,000 Li.”
Literal meaning: “The 10,000-Li Flying Range Of The Roc.”
Perceived meaning: “To have a bright future” or “To go far.”

This proverb/idiom comes from the book of Zhuangzi or Chuang Tzu. It tells the tale of a huge fish that could turn into a gigantic bird. This bird was called a “peng” and was many miles long. This legendary size allowed the Peng to fly from the Northern Sea to the Southern Sea in a single bound.

Wishing someone “a Peng's Journey of 10,000 Li” will imply that they can travel far without stopping and will have great success, a long career, and a prosperous future.