PSP. Watched so much hentai on that system that I couldn't live without it. These days you have phones if you want to watch porn on the go but back then? PSP was the shit!
Oh and it could also play games as well like Dead or Alive Paradise
PC Specs: CPU: 7800X3D || GPU: Strix 4090 || RAM: 32GB DDR5 6000 || Main SSD: WD 2TB SN850