Originally Posted by DoubleJ
There is a pedestrian underpass to the north of Ikebukuro Station, between the policebox and BIC Camera on the east side and coming out on the west side between the North entrance of Ikebukuro station and the "entertainment" district of Ikebukuro. Heading south from there, keeping Ikebukuro Station on your left, will bring you to the Metropolitan.
The Metropolitan is an easy walk from the station. It is FTer friendly with free internet service in the business center. The underpass goes through the basements of the train stations and the department store (food section). The more favorable exit for you closes at 11 pm, but there is still another open on the west side.