The male protagonist is the younger brother of the Butterfly family. He is a reborn person. He was a decent person during his lifetime (no)
During his lifetime, he was unable to walk due to illness, so he could only keep studying. Because he was very talented, he knew a lot of scientific and technological knowledge.
Bring the knowledge in your brain to the Taisho era and use technology to realize your dream of killing ghosts.
The male protagonist's character is a bit extreme due to his long-term absence from the world. He is very annoying in the first chapter. Anyway, it annoyed the author.
Mission: Technology changes the world