Keitai means cellular or mobile phone in Japanese. Nowadays, most everyone has one, especially in Japan. We use them mostly to communicate with others either verbally or by texting.
The latest phones can be used as computers designing graphics, recording images, video and sounds. We perform some of our most basic tasks like scheduling our days and work on our keitai phones. To be without one seems almost impossible. For someone to ask us to turn it off is upsetting.
If turning off your phone for a few minutes seems impossible, you may not want to ride on a Hankyu train. Trains now have signs asking passengers to turn their phones off. Where they used to ask passengers to sit in areas designed for those who wish to use keitai phones, they now go to the extreme.