"Underground idol" is an informal idol culture prevalent in Japan. These idols usually come from underground bands or independent music groups. They accumulate fans and popularity by performing in bars, clubs, concert halls and other places.

"Red hair" may refer to the nickname or nickname of an underground idol. Specifically, this underground idol may be a person with red hair, or their music style and performance style may be described as "red".

As for what this underground idol specifically tells, we may need to further understand it according to specific music groups, performances and works. Generally speaking, however, the performances of underground idols usually include songs, dances and interactive sessions. They may tell their own stories, share their musical ideas or interact with the audience. These performances usually pay more attention to emotional expression and personality display than commercial marketing and mass entertainment.