"2075: MEISTER TITANO'S COUNTERATTACK"
Written by Yukiko Takayama, the author primarily responsible for 1975's Terror of Mechagodzilla, this 7-chapter side story acts as a continuation of the movie, taking place 100 years in the future in 2075. Here, the body of Katsura (referred to as "L・K" or "Lady Kay") is found by a mining corporation, which also has in its possession the revived form of Titanosaurus as a cyborg, Mecha-Titanosaurus (referred to in the story as "Titano" or "Meister Titano"). As a revolution begins to unfold within the corporation, the paths of Katsura and Titanosaurus cross once again...
The full story can be found in the Japanese mook, "Tokusatsu Hiho vol.5", while an English synopsis of the story is mentioned in John LeMay's "The Big Book of Japanese Giant Monster Movies: The Lost Films":
[...] Set 100 years after the events of Terror of Mechagodzilla in 2075, Katsura is revived by a deep sea mining corporation. The corporation uses thousands of human androids with A.I. to do their bidding and in their midst is a revived cyborg version of Titanosaurus. When the robots, led by the Mecha-Titanosaurus, revolt and attack Tokyo, Katsura is called in to deal with the situation. In the story's last moments, Katsura boards a submarine which is attacked by Titanosaurus. He recognizes Katsura floating in the deep water and picks her up in his hand. The two have a final moment of reflection wherein both realize they are cybernetic shells of their former selves and Katsura drowns in the depths.
https://www.tohokingdom.com/blog/2075-m ... anslation/