In This Life, The Greatest Star In The Universe - Chapter 122:

“Kill Hamyuts Meseta”

A story about a world where all dead people become “Books” and are housed in a Library. The boy named Colio Tonies had his memories taken and a bomb transplanted in his chest. His life’s purpose is killing the world’s strongest Armed Librarian, Hamyuts Meseta. But, one day he gets his hands on the “Book” of a beautiful princess and falls in love at first sight. Furthermore, that love will cause Colio to get involved in a grand scale battle…

Originally born from a wealthy family, she ends up leading a vagrant life for fifteen years. However, when she is eventually found by her family, she falls into another devious plot and eventually dies tragically.

He became a teacher at the best magic academy in the empire.
….For being mistaken for someone else.

The strongest Hero in history, Nakamoto Keisuke.

He was summoned to another world in the spring at the age of fifteen years old, and when he successfully defeated The Demon King, he was already thirty-two years old. He had finished his role in another world and returned to Japan, but the reality that had been waiting for him was, “Middle school graduate with seventeen years of blank period” label. He couldn’t find a decent job and had no choice but to spend his days working part-time.

Before such a Nakamoto, a beautiful girl who self-proclaimed had come to return the favor, appeared. “I’m the reward for Hero who had defeated Demon King”, said Angelica, a girl who came from another world that persistently tempted Nakamoto to make her his wife. Together with a high school girl who looks like Elsa, his beloved girl that he lost in another world, Nakamoto with his cheats skills got caught in a harem life.