"100 mono Tobira" (100もの扉, lit. "100 Doors") is a song by Japanese singer-songwriters Rina Aiuchi and U-ka Saegusa. It was released on 14 June 2006 through Giza Studio, for the soundtrack of the Japanese animated television series Case Closed, for which the singers formed a special duo, Rina Aiuchi & U-ka Saegusa. The single reached number eight in Japan and has sold over 29,975 copies nationwide. The Japanese idol group, Sparkling Point were credited as the backing vocals for the song.