Height: 149 cm (4'10")
Ruka is an idol and a doujinshi creator under the pen name Fly Dolphin. She is Chiharu's friend.
According to Chiharu, Ruka has a similar past to Hayate, having been abandoned with a large amount of debt, namely, 150,281,000 yen. She aspires to be a professional mangaka. Ruka's pen name, Fly Dolphin, was originally the name of the performance office her parents used to own.
She eventually realizes that she is in love with Hayate and confesses to him, but he rejects her because he is working as a butler for Nagi. Ruka challenges Nagi to see who will sell more copies of their doujinshi. A sum the height of Hayate's debt will be the prize.
