Daimon station is a subway station in Minato ward, Tokyo. It serves Toei Oedo line and Toei Asakusa line. It is not served neither by Tokyo Metro line nor JR line but JR's Hamamatsu-cho station is in a vicinity, easy to transfer via ground level.
The station had 4th most ridership among stations on Asakusa line, even more than Asakusa station and 2nd most ridership among stations on Oedo line, after Shinjuku station.
Around Daimon station is typical business district but there are several tourist destinations such as Zojo-ji temple and Tokyo tower. Then, the station is important in case you are using Haneda airport. There are direct trains to Haneda airport via Asakusa line and Keikyu line. Or you can transfer to Hamamatsu-cho station which Tokyo monorail connects to Haneda airport too.