Saitoh was doing a reading of Tetsu but it was trick of Shinpachi, Sanosuke, and Heisuke to see who Tetsu liked. Saitoh read that Tetsu can't get this person off his mind from the past and is still alive today. Yamanami invited Tetsunosuke to Shimabara so he could have fun and forget about what Saitoh said. To Tetsu surprise he found Saya there who worked as a servant. (thetvdb.com)