Additionally, as he and his crew were unable to wait for Jiang's ship due to their hectic schedule, Takeuchi took a cruise ship instead, and was delighted to discover that the accommodation was both luxurious and comfortable.

Venturing through the Three Gorges, he visited Yichang in Hubei province, where he was amazed by the city's ship lift — the largest of its kind in the world — a marvel of engineering that effortlessly hoists vessels weighing up to 3,000 metric tons up a vertical span of 113 meters, and which is a testament to human ingenuity amid nature's splendor.

"When I moved to China in 2013, life wasn't as easy as in Japan. But now, living in China feels more convenient. When I went back to Japan earlier this year, I realized I had to wait in line for a cup of coffee, whereas in China, you can order ahead on your phone," he says, adding that he hopes the documentary will help Japanese audiences get to know China better.

The sociable and observant director also turned his attention to the people living along the river.

At a dock in the famously mountainous city of Chongqing, he focuses on a group of workers using bamboo poles to carry luggage for passengers, who are known as "bang bang", the word for porters in the local dialect. His attention is seized by a 71-year-old, who has worked as a porter since 1994, and who earns 40 yuan ($5.5) per trip, even in scorching summer temperatures that can reach 40 C.