It sounds like you are referencing a specific scenario or story titled "Payback Touching on a Crowded Train" featuring a character named Mizuki (and possibly the "I" indicates a first-person narrator).
The train stopped at another station, and more people piled in, making the space even more unbearable. Mizuki was squished between a businessman checking his phone and a young mother trying to soothe a crying baby. Her earlier accidental touch now seemed like a distant memory, replaced by the urgent need for the train to reach her destination. payback touchinv a crowded train mizuki i
Setting: A high-pressure, claustrophobic Japanese commuter train. It sounds like you are referencing a specific
Title: The Infuriating Experience of Being Touched in a Crowded Train: A Personal Account by Mizuki and more people piled in