1 R-Gacha normaly give a waiting time of 50 min, but it can sometime give 1:30, 2:00, 2:30 and longer waiting time.
I so players can in teory get any reward that 3 R-Gacha can give just with 1 R-Gacha but chance are very small.

I tried 1 R-Gacha more than 100 time I got R-Gacha 10 times and N-Gacha 2 times and SR-Gacha 0 times so far.
Just guesing maybe chance for SR-Gacha is 5%*5% = 0,25% or maybe less.

To get SR-Gacha doing doing 1 R-Gacha each time takes on maybe 400 R-Gacha while 3 R-Gacha each time only takes maybe 20-30 tries = 60-100 R-Gacha.

1 R-Gacha is very effective way to get R-girl but we still need to find good way to get SR and N girl.

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It seem i'm not the only one having hard time getting the N card. They are availible till when ?