Their songs played in regular floors and 10F/20F have following naming convention:
Regular floors: a single English word that contains letters i, s and e. Each song has three variations and each variation has one letter replaced with a number.
Songs that include a 1 instead of an i are played from 1F to 9F
Songs that include a 2 instead of an s are played from 11F to 19F
Songs that include a 3 instead of an e are played from 21F to 29F
10F and 20F: every instance of the letter O is replaced with Greek letter Θ (theta).
Etymology
Names in other languages
The name of the artist is the same as English in all languages except for Japanese.