I don't know where to find the answer so I hope someone can enlighten me on this.

I will be staying at the Metropolitan on the westside late nov to early dec. I usually stay at the Sunshine City Prince on the eastside and am used to the nightlife there having never ventured anywhere on the westside past the Liberty store right by the station. Now here's my question: how late do the underground passages at Ikebukuro station stay open? And if they do close at a certain time and I've missed the cutoff, how do I get to the westside (aside from waiting till they open in the morning)?

Any help is greatly appreciated