Fantasy: There Are so Many Wastes in the World, What's Wrong with Adding Me to the List?

The protagonist travels through time and is bound to the system. He originally wanted to live a life of being a salty fish and being quiet and a waste, but he was tempted by the system to embark on the path to immortality. He only wanted to dream of becoming an immortal for a thousand years and be an endless salty fish. This novel and its characters are purely fictitious. Any similarity is purely coincidental and should not be imitated.