Rūju no Dengon (ルージュの伝言, Lipstick Message, Message in Rouge, Rouge no Dengon) is the fifth single by Japanese singer-songwriter Yumi Arai, released in February 1975. This was her first single to enter the Oricon Singles Chart.

Rūju no Dengon is the lead single from the album Cobalt Hour. Its coupling song Nani mo Kikanaide was also included in the album.

The meaning of the lyrics shows a girl's actions after finding out that her boyfriend cheated. The song was used as the opening theme for the Ghibli movie Kiki's Delivery Service. The ending theme of the movie was Yasashisa ni Tsutsumareta Nara (album version), which had been included on her 1974 studio album MISSLIM.

Tatsuro Yamashita, Minako Yoshida, Taeko Ohnuki participated on the chorus of the song. Masataka Matsutoya, who was in charge of the arrangement, said, "The members of the tour band were asked to participate in the recording once in a while, and although it was OK, the quality of the performance was inferior to usual, so there was no response. After that, I added strings, but I felt that it was 60 points, so I thought that I could not make a record as it is. Then I came up with the idea of using Yamashita for the chorus. He had a connection with the chorus in the past.^[1]

After that, Yamashita gathered Yoshida, Ohnuki, and Kayo Ishū to make a chorus. That made it an outstanding American pop song. Therefore, Yamashita's power is very strong when it comes to "Rūju no Dengon". As a result, he pioneered Yumi's pop singer line.^[1]

The song also appeared in Makoto Shinkai's 2022 animated film Suzume as an apparent nod to Kiki's Delivery Service.^[2]