Death March kara Hajimaru Isekai Kyusoukyoku (WN) - Book 8 - SS: Pochi and Scary Thing

In the original lines of the novel, I was a villainess—used as a political tool by my father and older brother—who ended up dying at the hands of my future husband.

In the middle of a deserted island, a small boy wakes up with two sets of memories: one from his few years of life and the other from a man who lived to adulthood and achieved great things. When he least expected it, a powerful master appeared on the island and took him in as a disciple, revealing a shocking fact: magic exists in that world, and, thanks to it, humanity managed to conquer the galaxy.

Liu Ming, since he was young, lived in a savage prison named Savage Island where the prisoners aren’t controlled by any guard or security. When the island sinks due to “mysterious” events, only a handful of people survive – those survivors are then pursued by the government.

On the other hand at another place two practitioners are worrying about what will happen to them because the young master that they were supposed to protect had died.

Their young master looks nearly like our MC
What will happen?

- Description from Novelupdates

After being reborn and living for 30 years, I realized that my life was actually a romance fantasy novel?…Where are you looking?Becoming a wizard’s s*ave, living as an experiment subject, then as an assassin, from a mercenary to a soldier, and finally becoming a knight.This is the story of a man whose life spans across different genres by himself.