His parents persuaded him to apply for the position after he graduated from university, saying that, as a young person, he should find a position where he could realize his value, instead of wanting too much from life.

At first, he worked in a team of 15 people. However, when commercial logging was prohibited, many of his colleagues moved away with their families, members of which had been working in the logging industry.

"With fewer colleagues, I had to take on more responsibilities. But now, when I reflect on these experiences, I feel they are very meaningful. People have to endure hardship in order to grow," he says.

As the only one maintaining and repairing signal infrastructure in the border area, Chai has also become a link between the local border defense soldiers and grassroots workers and their families.

Wang Zhen from Qiqian station, Greater Hinggan Mountains branch of the Inner Mongolia Autonomous Region Forest Fire Brigade, has known Chai for more than 10 years.

He says the team members all consider Chai as an older brother. Every time Chai goes to their station, he always contacts them, and nearby residents, in advance to ask if they need him to buy anything for them.

"Through our conversations, I know that he wanted to become a soldier as a child. I feel that, although he is not one, he has a soldier's qualities, such as resolution and willpower in the face of challenges," Wang says.

Wang remembers one incident vividly. It happened in December 2015, when their station lost its signal. Chai ran some tests and found that the fiber-optic cables had been broken more than 20 km away. For an entire week, he took a few firefighters out with him early in the morning, dug the cables out and fixed them.

"There were many such occasions, which we thought we faced an impossible task, but he persisted as long as he could see a glimmer of hope," Wang adds.

For the past decade, Chai has observed changes in the region: Roads are being laid and improved, more telecommunication base stations have been built, and it is easier for the residents to contact others or use the internet.

"Although I'm the only one who has stayed here for 14 years, I am never alone, as I've always been supported by my family, the locals and the company," Chai says.

"It is my mission to work among the forests. There is still a lot to be done. For me, the fundamentals are to do my job well and be a responsible and useful member of society."