https://youtu.be/8XiwapsWPU4?t=9631this is the moment that Gura felt her menstruation coming out, you can see her looking down to check on her crotch.
https://youtu.be/8XiwapsWPU4?t=9643here she says "i might need to..." then pauses and her pupils show that she's rapidly looking at random directions instead of looking at the listener(chat) this indicates embarrassment and that her brain is trying to come up with a false excuse to leave.
https://youtu.be/8XiwapsWPU4?t=9650here she says "pee" in a monotone way that indicates she wasn't sure about her choice of words, another sign that it's just an excuse.
https://youtu.be/8XiwapsWPU4?t=9659here Gura uses "i should probably" instead of "i have to" this means that there's no real urgency in her necessity, unlike someone who really needs to pee.
After that she leaves for about 1:45min
females can actually urinate faster than males, even with a full bladder they should take about 20 seconds to finish and about 15 to wipe themselves then a few more seconds to wash their hands, the whole process should take not much more than 60 seconds considering her toilet is very close bacause she felt the necessity to avoid any possible noises with the loud technical issues screen on top of just muting the audio. 1:45min would be too much time, that way we can assume that she spent 30 more seconds to open and put a pad on.
