Sukuna does die in the manga. The way it happens is quite dramatic and ties in with many other elements of the story, adding depth and tension to the overall narrative.
In the 'eris and rudeus light novel', the story begins with their meeting. Eris is from a noble family and has her own set of values and goals. Rudeus, on the other hand, has his own past traumas and ambitions. As they travel and interact, they encounter different races, face magical threats, and also experience the ups and downs of their relationship. Their story is set in a fantasy world full of magic, monsters, and political intrigue.
Well, in addition to Rudeus, Eris, and Sylphiette, there is Paul. He is Rudeus's father and his actions and decisions have an impact on Rudeus's journey. Lilia is also a notable character. She is a maid in the family and her presence adds to the family dynamics within the story. These characters together form the core of the 'Rudeus Light Novel' and drive the plot forward through their interactions.
Well, one unique feature is its complex character development. Rudeus, for example, starts as a flawed character with many insecurities and gradually grows throughout the story. Another is the detailed world - building. It creates a vivid and immersive fantasy world with its own rules, magic systems, and cultures.
Nope. Ryomen Sukuna has no basis in reality. It's a product of the creative minds of the writers and illustrators who designed a captivating fictional character for the enjoyment of the audience.