pink area at platform, Shinjuku station

What is the pink bright area ? Someone please help translate ?

http://saywhatjapan.com/translate-japanese/transportation/pink-area-at-platform-shinjuku-station/2018/05/https://i0.wp.com/saywhatjapan.com/wp-content/uploads/2018/05/DSC_0994-768x432-3.jpg?fit=768%2C432https://i0.wp.com/saywhatjapan.com/wp-content/uploads/2018/05/DSC_0994-768x432-3.jpg?resize=150%2C1502018-05-24T14:52:52+00:00TSTRANSPORTATIONplatform,sta,stationWhat is the pink bright area ? Someone please help translate ?TS stmmy12o17@gmail.comAdministratorSAY WHAT !?, JAPAN ! - translate "THE" Japanese in towns