I am the first leviathan eater of humanity again:Futa - Chapter 35: First day of military lessons

Her ex-boyfriend was snatched by her step-sister. Not only that, she accidentally lost her virginity to him due to her step-sister’s schemes.She was nearly confined to her home until he came along. He rescued her from that nightmarish place, if that place can even be called a “home.”He, dashing and powerful, seems to have everything. Yet he suffers from an odd illness where he feels nauseated whenever a woman is within three meters of him. She, however, is an exception. From that fateful day on, their paths cross. He strives to win her heart, and she, too, starts to develop feelings for him.But as the story unfolds between the two, her ex-boyfriend’s growing mixed feelings and the appearance of his fiancée threaten to put an end to the budding love between them…

I originally thought this was a world like an ordinary urban novel…Drawing comics by myself, traveling is pretty good.
But tell me, what happened to this magician called “Emiya Kiritsugu” who jumped on my face?
Who changed the settings?
Currently involved in the content of “F/Z”, “F/SN”, “Fantasy Carnival”, “The Emiya’s Meal”, “The Holy Grail of the Imperial Capital”, “FLA”, “Elmello II Event Book”, “FGO”, “FE”, etc.
Others related to “JOJO’s Bizarre Adventure”, “Rebellious Lelouch”, “Persona 5”, “Attack on Giant”, “Death”
“FGO”, “FE Series”, “FA”, “FSF”, “Cangyin”, “Magical Girl Illya” will be involved next…

- Description from novelbuddy

A man who was once called the world’s strongest agent ended up becoming a teacher after his retirement, to train a new generation of agents. After many years of training his disciples, he was killed at the age of 60 by a secret organization’s ruse and was reincarnated in another world with his memories intact. Though he was surprised by the existence of magic and the strange species in that world, he quickly adapted to his condition as a newborn and took advantage of it. He acquired special magic and gained a massive amount of strength thanks to his rigorous discipline, in order to reach his goal: Resume his career as a teacher which he left halfway through in his previous life. This is the story of a man, who, based on the memories and the experiences of his previous life, became a teacher who travels through the world with his students.

In a monstrous post-apocalyptic setting, this is a story of how a lowly Inventor, Lance, conquered a nation governed by immoral group of Scientists called The Corporation. He grew and climbed up to the highest rank possible as a Scientist with his inventions and side businesses. Eventually, he became a weapons inventor, building weapons to two opposing sides. In doing so, Lance always crossed a dilemma. How could a nobody topple the most powerful government? How could one overcome circumstances beyond his grasp, especially in a world filled with monstrous mutations called the Abominants?