Back to Siesta with Swire and Eyjafjalla looks like we will learn about Eyja parents.

The limited banner feature:

• Swire the Elegant Wit

• Poncirus
  and limited operator of this banner

• Eyjafjalla the Hvít Aska

As it is Limited banner you will get coupon for 10 pulls and 1 pull a day until the end of the banner. Old Limited operators that can be pulled as off banner with x5 weight would be

• Ch'en the Holungday

• Gavial the Invincible

So according to So Long Adele - Farming Guide from gamepress
Efficiency (based on all possible stage drops): Manganese > Aketon > Crystal

The event stages will be released in parts:

[A Holiday at the Hot Sprigs]: January 16, 2024, 10:00(UTC-7) - February 6, 2024, 03:59(UTC-7)
[Treasurehunting in Siesta]: January 23, 2024, 16:00(UTC-7) - February 6, 2024, 03:59(UTC-7)
[Surfing the Lava]: January 30, 2024, 16:00(UTC-7) - February 6, 2024, 03:59(UTC-7)

Good luck with pulls!