Since I don't have access to the details of this novel, it's difficult to determine exactly who the king of the cave is. It could be a protagonist who has a significant role to play in the paradise - like life described in the novel. It might be a figure that the whole plot revolves around, perhaps with a mysterious origin or a grand mission.
In the context of this novel, 'paradise life' might refer to a state of existence that is far from the ordinary. It could involve having extraordinary experiences, being in a place of great beauty and harmony. For the king of the cave, it might mean having supreme power, living in a utopian - like environment, perhaps with no strife or suffering. It could also imply a spiritual or emotional fulfillment that is rare in normal life. This kind of life could be a central theme in the novel, driving the plot and the actions of the characters.
Well, perhaps we can expect an adventure-filled story where the cave king discovers and enjoys the pleasures of a paradise life. Maybe he'll face some challenges along the way to maintain that paradise.
The 'long live the king manga novel' could be about a historical or fictional king. It could explore his rise to power, his relationships with other characters like his advisors, enemies, and family. It may also depict the culture and society of the kingdom he rules. Since it's a manga - novel, it might have elements that are unique to Japanese manga styles, such as exaggerated expressions and dynamic action scenes.