One-Time Domains are unique Domains that are denoted by a smaller blue circle on the Map that provide a set reward upon the first time a player completes them. They are still open after the first completion but will not offer any rewards. One-Time Domains provide an early boost to Adventure Rank through their Adventure EXP rewards and sometimes offer unique Food recipes, along with Primogems.
Until the area they are in is revealed by unlocking the corresponding Statue of The Seven, One-Time Domains do not show up on the map and cannot be teleported to, even if they have been unlocked.
One-Time Domains may be completed as soon as they are unlocked. Some can be unlocked immediately, while others cannot be unlocked until a puzzle in the area is solved.