Zenless Zone Zero will mark its second anniversary with the v3.1 update on 29th July, and developer HoYoverse has confirmed a crossover event with its sister title Honkai: Star Rail. Details of the collaboration remain unconfirmed, but it is expected to see characters exchanged between the two games, further linking HoYoverse's shared "HoYoverse" universe of titles. The update also brings a wave of new content and giveaways to mark the anniversary.

The v3.1 update introduces new playable agent Remielle Dan for the full duration of the update, followed by Sigrid in the second phase, alongside reruns for characters including Dialyn, Ukinami Yuzuha and Asaba Harumasa. Players can also claim a free S-Rank agent and W-Engine from a choice including Jane, Soldier 0 Anby, Hugo, Trigger and Lucia, receive up to 30 free pulls, and enjoy changes making the 50/50 gacha system less punishing. Additional content includes a new dungeon-crawler-style permanent mode, a summer-themed beachcombing minigame, and free swimwear and outfit unlocks for several characters.