D2 Events
Source: Transcripts from D2 Megaten's events, including Aura Gate Faction Events that were introduced around the game's second anniversary.
In its beta and conception phases, D2 Megaten didn't have time-limited events in the traditional sense with story text interspersed with battles. Rather, the "Aura Gate" randomized first person dungeon was intended to be an infrequently scheduled event.
Before launching, popular demand pushed the staff to make Aura Gate a permanent fixture of the game, and with it, an ongoing series of story based events with easygoing battles that don't necessarily tie in with the game's main story.
Mobile game contract writer and self-professed fan of yuri, spaghetti westerns, joshi professional wrestling, and Ryu Ga Gotoku 7 Inishi Kara was hired to write the story events. This arrangement is known to have started in the middle of 2018 when the story events began, and lasted at least up until producer Masafumi Tanabe's departure from Sega in December 2022. It's unclear if anybody else has been involved with writing events since, as credits were removed from the game.
Event stories range from light hearted goofy yarns, to handling more serious subject manner in an unusually considerate way. Very few of them play off of the story canon, though some events do lean on established background as an means to bring in new characters.