The answer is: "OST song" refers to the song in the OST. OST referred to the original music in movies, TV series, and other film and television works, and the song part was the OST song. According to the search results, some OSTs of movies and television works included some songs, such as the theme song of the TV series OST of " A Thought of Passing Mountains," many of Zhou Shen's OST songs, and Yu Kewei's Top Ten Classic OSTs. Therefore, an OST song referred to the song part of the original music in a film or television work.
I'm not entirely sure as I haven't read it specifically. But generally, a novel about 'drifters' might be about people who are constantly on the move, perhaps exploring different places, cultures, or just living a nomadic lifestyle.
The 'the drifters girl' story is likely about a girl who has some connection to the Drifters. Maybe she's a fan, or perhaps she has a personal journey intertwined with the group in some way. Without more specific information, it's hard to say exactly.
The OST lineup for the second season of Celebrating Years had already been announced. Among them, Li Jian sang the theme song " In My Lifetime," Zhou Shen sang the ending song " Excuse me," Liang Long, Liu Duanduan, Zhang Haowei, and Guo Zifan performed the promotional song " Aiya." These songs would bring more musical elements to the second season of " Celebrating Years," adding more emotions and atmosphere to the plot.
There were many social reasons for the emergence of the old drifters. The old drifters were mainly caused by the multiple structural forces of the market economy, social protection, traditional culture, and national systems, as well as the physical and psychological weaknesses of the elderly. In addition, the old drifters also encountered some problems in the process of adapting to urban society, such as mental health and psychological adaptation problems, as well as social barriers with locals. However, the specific social reasons were not explicitly mentioned in the search results provided.