Ryōka Yamakawa

Ryōka Yamakawa is a Gewehr user. Her Gewehr is an Ingram MAC-10 machine pistol.

She is in Seitetsu Class 5 of the second grade. She has, before her transformation, the appearance of a young idol for her age, but her appearance is that of a grown-up after she transforms to her Kämpfer form. Ryōka appears for the first time in the municipal library on the second floor

Ryōka seems to be afraid of everything, especially the Blue and Red Kämpfer.

Ryōka's voice actress, Kotomi Yamakawa, shares her surname with the character.