Opening hour of Ikebukuro Station

Hello, I have looked through various websites but cannot find the answer, so here I am. I have a 6.45am <edited> domestic flight leaving from HND and I stayed near Ikebukuro Station on the east side. According to Google Maps, the nearest and most convenient exit is exit 35 with an elevator since I will be bringing a large luggage.

I am planning to catch the first Yamanote Line train at 4.25am towards Hamamatsucho and transfer to the first Tokyo Monorail train at 4.59am to arrive at HND by 5.15am. While the transfer at Hamamatsucho is very tight (only 4 minutes according to Jorudan website), I am willing to take the risk.

This plan however depends on whether I can catch the first Yamanote Line and so arriving to the station on time is crucial. Since I also have a specific exit I’m planning to take, it is also important that that exit can be used and is already opened.

The question is then: what time does usually Ikebukuro Station open? Specifically, how many minutes before the first train leaves? And also is there any way to know the opening hour of a specific exit of a station with various railway companies operating from?

Another thing is that through Google Maps Streetview, I can see that there is a Tokyo Metro (TM) signage above the elevator of exit 35 which I assume meaning the exit is managed by TM. Does this mean this specific exit opening hour will only follow the timetable of TM lines? If it is then this is not ideal in my case since the first train of all three TM lines leaves at and after 5.00am…

Appreciate if any of you can share any advice or been in a similar experience!

by khunphey