It's the Tube (Metro acceptable) not the Subway :(

Yeah that’s just what they call it regionally like in America it’s the train the metro or the subway never the tube that’s more European/English just like the railway, mtr, the underground or the u-ban and in New York it’s specifically always referred to as the sub way in California it’s the train or metro sometimes even like the name like the blue line it’s different everywhere you go

I only say because this manwha is set in London lol. It's giving me whiplash reading about the London subway and soccer haha