Early releases often only featured Hymen as label name and for copyrights.
Catalogue number style:
¥0xx for the 12" series with stamps on the cover
¥4xx for LPs, CD3" etc.
¥6xx for promotional gimmicks (t-shirts, posters ...)
¥7xx for CDs
¥002, Instinctive LP by Ultra Instinct, will never be released.