Only Sense Online - Volume 2, Chapter 3 - The Unicorn and the Collapsed Elf

Elena, who spent her entire life as a cold-blooded female knight to avenge her family, ended up dying without claiming her revenge. When she opened her eyes she found that she went back into the past. By day she was a lady in a dress, and at night she carried a sword to change history and prevent her family’s destruction.

Vid: My time at Hogwarts is only seven years, and excluding holidays, that's only 266 weeks! Even if I could thoroughly read one book a week, 266 weeks is only 266 books! How many Magic Books are there in the Hogwarts library? Thousands upon thousands!Time waits for no one, so how can I not seize the time to study?! I will not allow anyone to disrupt my study environment—not even the Dark Lord!

In a world fractured by conflict and haunted by shadows of the past, Kokushibo—the first Upper Moon demon—meets his end, only to awaken in a new life. Reincarnated as Crimson, a child born into a different family, he carries the memories of a past he cannot escape. Burdened by centuries of guilt yet indifferent to the present, he resigns himself to duty—until an unexpected bond with his newfound family begins to thaw his hardened heart. As he struggles between the weight of his past and the weight of the new life, Crimson must decide whether he will remain shackled to his former sins or embrace the possibility of peace.

A man reincarnates in the body of a boy who suffered a tragedy, only to realize that he is in the world of My Hero Academia. What's even stranger is that his quirk seems to have the abilities of Nen and Haki.