Well, 'jana gana mana' is a very important part of India's heritage. Tagore penned it with deep love for his country. The real story behind it is about capturing the essence of India, with all its different languages, cultures and regions. It was created to instill a sense of pride and togetherness among the people of India. When it is sung, it unites Indians from all walks of life, whether they are from the north or the south, east or west of the country.
The 'Luca Gana Secret Story' could cover a wide range of things. Maybe it has to do with his dreams and aspirations that he has only shared with a select few. It could also be about a particular event in his past that had a significant impact on him but he has chosen not to make public. It might even be a story about his family or upbringing that contains elements he considers private.
Toge Inumaki is important too. His special cursed speech ability makes him stand out. Also, the principal of the school, Masamichi Yaga, is likely to be important as he is in a position of authority and has an influence on Gojo and the other students. There could be other characters like the members of different clans that also play roles in the complex web of the story.