After the events of the last quest in the series Genshin impact.
See article for full guide. "All Ghosts on Tsurumi: Where to Find, How to Start and Complete Quests".
Where to find Kito and Kin's ghosts in Genshin Impact
Ghosts hover on a small island west of the teleporter in the Autake Plains.
After the first conversation with the children, turn to them again and give one Cherry Blossom.
The ghosts will talk about the beach at Tirai Shrine - go there.
Ghosts of Kito and Kina on Tsurumi: Genshin Impact Map
In total, you need to bring four Cherry Colors to the visions. The first time during the first conversation and subsequent times with each finding of phantoms. To give the flowers again, talk to the ghosts.
When you find Kito and Cana for the last time, the phantoms will tell you it's time to leave and ask you to bring the Scented Sachet grandmother Una.
Reward
For helping the ghosts, the player will receive a precious chest.