The phrase "payback touchinv a crowded train mizuki i hot" appears to be a reference to from the mobile rhythm game Project SEKAI: Colorful Stage! (also known as Hatsune Miku: Colorful Stage!

Crowded morning train. Someone’s hand presses against my waist — “accidentally.” But the smirk says otherwise. Payback touch? Fine. I press back — harder. He flinches. The train sways. I smile sweetly. “Sorry, crowded, right?” Don’t start what you can’t finish. 🚇🔥 #NotSorry