Why do so many men line up around Ikebukuro station?

This is the most ridiculous and nosy question but I have to ask.

Around ikebukuro station, more specific, in front of Pino Restaurant a bunch of men line up almost every morning, around 9:30 am. I noticed that today it was full, as usual, but I’m not sure if it’s everyday, just sure it’s quite often.

I’ve seen a person giving them a piece of paper while they wait and I AM DYING TO KNOW WHATS GOING ON?? Is it to work? Is it to donate sperm? I see them line up and they are ONLY men, around 50, sometimes even looks like 100 men.

I hope my nosiness brings up something interesting.

Thank you