Denial of Digital Distribution: The ten ZUN's Music CollectionCDs and five Akyu's Untouched Score soundtrack albums were released between 2002 and 2016, but didn't appear on iTunes and Google Play Music until 2018, and didn't become available for streaming until 2021. However, Dr. Latency's Freak Report got delisted from the US iTunes store in 2020, and has yet to resurface.
Five years passed between the releases of Magical Astronomy (2006) and Unknown Flower, Memerizing Journey (2011) in terms of just albums alone, and about six passed concerning the continuation of the Sealing Club's story in Trojan Green Asteroid (2012).
Five years passed between the releases of Dateless Bar "Old Adam" (2016) and Rainbow-Colored Septentrion (2021).
Narrative-wise, eight years passed between the releases of Dateless Bar "Old Adam" (2016) and Taboo Japan Disentanglement (2024), which ZUN even lampshaded in his official announcement for the album, joking that it had been so long that people may have forgotten all about the Sealing Club's story.
Shrug of God: "Maribel Hearn" is technically a Fan Nickname, as there has never been an official romanization for her name, マエリベリー・ハーン. While ハーン is heavily implied to be Hearn, as noted when ZUN was asked about her connection to Yukari Yakumo and he pointed to Lafcadio Hearn in his answer, the romanization for マエリベリー remains a mystery; when he was asked about it at Anime Weekend Atlanta 2013, his only answer was: "I don't really know".
Teasing Creator: When asked about the nature of Maribel's connection to Yukari Yakumo, ZUN merely grinned and answered "Well, there was this guy called Lafcadio Hearn...".
General Trivia
Magical Astronomy has the largest amount of original songs in an album at six.
in his answer, the romanization for マエリベリー remains a mystery; when he was asked about it at Anime Weekend Atlanta 2013