1518, pronounced ichi-go ichi-e,[7] is the first studio album by the Japanese girl group @onefive. It was released in physical form on February 2, 2022, by the record label Amuse Inc. A digital release followed shortly after on February 14, 2022.[8]
The album was titled 1518 because @onefive was formed in the year that all of its four members turned 15 years old, and the album was released in the year that they would be turning 18 years old.[9] The title, as is the case with the name of the artist, is also a reference to the concept of ichi-go ichi-e, which the members value.[10] The title, track sequence, and visuals of the album were decided by the members of @onefive themselves.[11]
The song "1518" on the album marked the first time that the members wrote their own lyrics. Fujihira and Yoshida came up with the words they wanted to include in the lyrics, and Mori and Aritomo gave shape to them.[12] The song expresses gratitude towards their fans.[7]
"Underground" was choreographed by the four members of @onefive, marking the first time they created their own choreography.[13] Its creation was documented in a four-part documentary series released on YouTube titled Their Underground (彼女たちのUnderground, Kanojo-tachi no Underground).[14] The members were also intimately involved in the production of the music video for "Underground", sharing their ideas on hairstyles, makeup, outfits, visuals, and cuts.[15]
The choreography for the debut single "Pinky Promise" was created by Mikiko.[1] The dance troupe Elevenplay, which is directed by Mikiko, choreographed "Mada Minu Sekai", the instrumental dance version of "Shizuku", "BBB", and "Lalala Lucky".[16]
The album also highlighted @onefive's desire to be "a group that grows up with the same generation".[17] All of the songs apart from "1518" had their lyrics primarily written by a female high school student and singer-songwriter called Yura, who was the same age as the members of @onefive. Before writing the lyrics, she would listen to the thoughts and opinions of the members, making them more relatable to her peers.[18] Further highlighting their generational focus is that the music video of "Lalala Lucky" was produced in collaboration with students of N High School and in cooperation with Adobe.[19][20]
The outfits worn by @onefive in the music video for "BBB" were a collaboration with the fashion brand Apres Jour.[21] The single "Just for You" was featured in the 2021 Christmas commercial of the Japanese jewelry brand The Kiss.[22][23] "Lalala Lucky" was featured in a web commercial for the hair dye brand Beautylabo.[24]
A special edition of 1518 was also released on the same day as the standard edition. While it lacked the three instrumental tracks, it included a 24-page photo book and a Blu-ray disc containing the recording process of "Pinky Promise", a digest of @onefive's pajama party livestream, and the director's cut version of the documentary Their Underground.[25]