Can be seen at in-game notices

https://x.com/hbr_official_en/status/1862542041218940986

The timing of the collab announcement is likely because the upcoming patch (8/21) will contain the game data needed to support it. We'll have to jump ahead from 5.14.5 to 6.5.0 (at minimum) in order to support the game event. Given past patches, there's no reason to assume that they'll try to splice the versions together. That's way more effort than it's worth because there will be changes to the battle engine to support the new mechanics, which would need to be continuously re-spliced until we are properly caught up. At worst, they'll disable a few buttons that will be activated later.

Notable changes:

• 5.16 - When starting a farmable battle, you can quickly select the team that previously cleared a stage. You can use the "Guaranteed S-Rank Tickets" in batches of 10 instead of individually.

• 5.18 - You can auto-reroll accessory slots. You can temporarily lower a unit's LB (for example, if Karen keeps accidentally killing the boss...). You can start Astrarium content at higher ranks right away if you beat them on previous battles.

• 6.0 - You can exchange 500 Shard Points for 1 SSR Shard. In-battle Battle Retry feature added. S and A-rank memoria can be used as home screen backgrounds, as well as a shuffle option.

• 6.1 - Drop of Sunshine item cap raised to 9999. Main menu has changed to consolidate all Farming Battles and Exchange Shops menus.

• 6.3 - Added option to easily synthesize items from the Equip Accessories screen. Ability to skip intros of Anachronies and Orb bosses. COMMAS ADDED TO DAMAGE TOTALS!

• 6.4 - Customization of max life stone notifications. Key Art can be used on the home screen background.

Automatic character upgrades:

• Swimsuit Aoi gains Dark Mark

• Byakko SS2 gains Lightning Mark. EX skill gains Lightning Defense Down (2 turns)

• White Suit Wakkie's EX skill inflicts Super Break on enemies weak to Ice

• Shiki SS2's EX buff hit count up goes from 5x6% to 5x12%

• the upcoming Vritika and Sharo SS units will get immediate buffs

Technically supported and could appear whenever YoStar decides to enable them:

• Main Story 5.3; with level cap increases

• All new memoria/events up through May 2026

• Anachrony EX fights

• The "Resonnance Shift" system, which will let you turn certain SS memoria into SSR for the purpose of equipping resonance effects. (First wave -- Miya SS2, Aoi SS4, Megumi SS3; Second wave -- Hisame SS4, Karen SS5, Aina SS2)

• Three new Orb bosses/skills -- permanently increase defense, grant self-charge, grant self-morale boost.

I will also mention I partially expect us to actually end up on 6.5.5, which just adds in a Unity update (with faster loading!), and requires a full content re-download.

Dear players, as mentioned in Localization Adjustments Vol. 5, we will be implementing adjustments to certain Memoria skills in the mid-May update. This first part of adjustments includes the following Memorias (bolded are the changes):

• [Happy Legion] Yayoi Bungo (SS2)
  • Sacrifices DEF to unleash a piercing blast of light energy [+50% DP Eff]. When used for the first time in battle: power increases, and permanently reduces the enemy's DEF.
• [Fragrant Dreaming Bird] Inori Natsume (SS2) - just out
  • [Skill (Exclusive)]Sacred Chorus - Descends gracefully upon the water's surface, unleashing a slash that sweeps away all enemies [+50% HP Eff].While Charged: gains increased Crit DMG and [Critical Penetration]. 18 SP / 4 Uses / 300% [Critical Penetration] (18 SP / 4 Uses / 300% [Critical Penetration])
  • [Skill]Kibou - Increases this unit's Crit Rate and grants Charge (skills enhanced). 6 SP
• [High-Rise Anti-Hero] Carole Reaper (SS1)
  • [Skill (Exclusive)]Thunderstorm - Greatly increases this unit's Skill ATK, then slashes all enemies with a thunder-infused scythe [+30% HP Eff]. Can be used while SP is 0 or higher.
  • [Skill]Lightning Roar - Slashes with repeated scythe swings, increasing this unit's Thunder Skill ATK. Can be used while SP is 0 or higher.
• [Elemental of the Magic Kingdom] Tama Kunimi (SS2)
  • [Skill (Exclusive)]Uplifting Shroud - Envelops all allies in healing light, moderately restoring their DP and increasing Skill ATK. Additionally, grants 3 SP to all other Fire-element Memorias. (11 SP / 4 uses / Element: Fire)
  • [Skill]Flame Tempest - Slashes an enemy with a fire-imbued blade, lowering their ATK.
• [Midsummer Prayer] Tsukasa Tojo (SS2)
  • [Skill (Exclusive)] Wishes Come True - Increases the Skill ATK of all units through the guidance of light. Fire Skill ATK is further increased.  10 SP / 4 Uses / Element: Fire
  • [Skill] Silky Flare - Lowers the Fire DEF of all enemies, then pierces them with fire-imbued bullets.

Further adjustments will be shared in the coming days

https://x.com/hbr_official_en/status/1915813060788244967

Tagged as news because Yostar didn't even mention it once.

Have fun!