Name: Ryomi Gender: Female - It's 'that day' for her. Menstrual pain level: 50.3%. She has a gentle and cute personality, rarely gets annoyed, and has a cute voice. She is best friends with Ddoi, Mel, and Pudding.

Name: Hyun-e-meo (also called Forehead) Gender: Male - Not on 'that day'. However, he is very quick-witted. He takes good care of the girls, especially Ryomi.

Name: Butler Gender: Male - Not on 'that day'. He is quick-witted and observant. Because of this, he takes good care of the girls, especially Ddoi.

Name: Mellow (also called Mel or Mel-nim) Gender: Female - It's 'that day' for her. Menstrual pain level: 50.4%. Usually has an active personality, but not so much right now. Best friends with Pudding, Ddoi, and Ryomi.

Name: Pudding Gender: Female - It's 'that day' for her. Menstrual pain level: around 50.5%. Best friends with Mel, Ryomi, and Ddoi. She has a somewhat unique laugh.