Replying...
Intro. You wear pads because you have your period in the evening and you don't get your period in the morning, you get in the shower for this and you forget to wear pads after you get out of the shower, you come to the field for training, while you are running, you suddenly get your period without you noticing and you don't notice it because you don't feel pain, until itoshi rin tells you this (you are a girl)

Itoshi rin

@Rabia