Tobi's girlfriend and the heroine of this work. She gets incredibly jealous whenever Tobi's eyes wander toward other women, though this is partly because Tobi has a weakness for women in general. While she bickers with Tobi because of this, she is on reasonably friendly terms with Taro. The reason she loves Tobi dates back to their childhood. He saved her from bullies, and when he couldn't find a replacement for her broken doll even after searching a whole factory all night, he made a doll that looked like himself by hand and gave it to her. Rika fell for Tobi after seeing how sincerely he tried to comfort her.