It's A Man Who Hits A Weak Female Student With Everything He's Got, And I'm Going To Crush His Rotten Sense Of Justice.

Yamada is a dull, unremarkable salaryman in his forties. He releases the stress of work and home life by bumping into random people on the street as a "bumping old man." That was his only sense of superiority. One day, he bumps hard into a strong-willed schoolgirl named Ruru on her way to school, earning her fierce anger. Her words of contempt, "You're the worst! Disgusting!" make Yamada unable to bear it for the first time. He uses a hypnotic app he got online to brainwash Ruru. At first, he only intends to make her apologize and respect him…