Itadori did indeed die in the manga. His death had a significant impact on the story and the other characters. It was a turning point that led to many new developments in the plot.
Itadori is quite powerful in the manga. His strength lies not only in his physical abilities but also in his determination and the unique powers he acquires along the way. He's able to face off against formidable opponents and come out on top more often than not.
Well, Itadori's journey in the manga has been full of surprises. He's had to deal with curses, make difficult choices, and his relationships with other characters have evolved in complex ways. There have also been moments of great personal sacrifice and growth for him.
Since I'm not familiar with a specific 'Passion Yuuji' novel, in general, a novel might have unique characters. Maybe the characters in this novel have strong emotions and passions that drive the plot forward.