Ryōka Yamakawa

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

Ryōka 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 woman after she transforms to her Kämpfer form. Ryōka appears for the first time in the municipal library on the second floor. In the anime, she appears first along with two other White Kämpfers who smile at Kaede at the hotel pool.

Ryōka seems to be afraid of everything, especially the Blue and Red Kämpfer. She says "I'm sorry" when she makes a mistake. In the Anime, she is more similar Akane in shyness but more like a dislike to doing bad things while doing them willingly for Kaede.

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

Ryōka's personality is similiar to Ururu Tsumugiya from Bleach.