Well, it's hard to say exactly. The manga doesn't provide a straightforward answer. Maybe it's meant to keep us guessing and let our imagination run wild.
Overall, the ending of the manga shows Onizuka achieving his goals and leaving a lasting impact on the school and its students. There are some unexpected twists and turns along the way, but it all comes together nicely in the end.
The significance lies in its ability to evoke strong feelings and set the tone. It enhances the overall experience by emphasizing the drama and importance of the story's themes.
Sometimes, it's the audience's interpretation. Different listeners might perceive and construct their own version of who lives, who dies, and who tells the story based on their emotional response and imagination when listening to the instrumental.