Rinko and Tsukasa have known each other since high school. They are good friends and often talk on the phone and walk together. Today, Shirokane invited Tenma to visit her. Tsukasa of course agreed. When she came to her friend, she took him to her room. There was an assembled synthesizer. Tsukasa looked at Rinko for an explanation. She looked away and said. "Do you want... to play together?"