|“||Good memories must not be sad. It's so sad when Homo religios invents fantasies to cling to.||”|
–Kagari, Shizuru Route
Terra Route focused on Kotarou and Kagari seeking this, so that humanity continues to thrive.
When a Key is born, they look to the memories of every human being to search for a good memory. It is a familiar word to druids, but its true nature is unknown even to the Key. However, a Key can recognize it once it finds it.
Near the end of Terra Route, Kotarou concluded that a good memory for Kagari meant humanity carving their future, even beyond the Earth's survival.
Kagari was unable to find good memories, and only a shell of her remained as Salvation proceeded. Kotarou could not understand what she meant by good memories not being sad.
In the shelter where very few people evacuated, a superhuman named Awaji found a book on what seemed to have been written by a person from a previous civilization. Its final chapter is translated as follows:
"The Mǎo's (Key's) destruction does not depend on humanity's growth, prosperity, or behavior. I do not know if we have walked the right path. But if an observer of this planet ever comes to judge us... I can only pray we have matured well as a species."A person in the shelter who found out about this prayed that the next humanity will create better memories.
Kagari, in one of her momentary return to her emotionless self, muttered the word.
When Gaia was about to initiate the Song of Destruction, Kagari broke down, unable to find good memories. While Salvation succeeded and humanity was wiped out in the process, Kagari was nonetheless fond of what she found: coffee and the members of Occult Club.
When Kotarou asked Kotori about what she knew about the Key, all she knew that it was looking for a good memory. She never knew what it was.
Terra Route Edit
Kagari asked the help of Kotarou to seek good memories, Neither Kagari nor Kotarou knew what it was, but he deduced that stopping the war between Gaia and Guardian might create it. Because he saw her as the only place he could belong, he agreed to do it.
She became increasingly weak and despairing as time passed and Gaia prepared to initiate the Song of Destruction. Inside a room where Kotarou, Kagari and Kotori hid, he tuned in to news, which was reporting on environmental efforts, but this was not taking her attention at all. She continued to despair, until news of a faraway habitable planet came, and she was markedly interested. She wanted humanity to go there before Earth runs out of resources, but Kotarou felt that it was impossible given the current technology.
When Kotarou was finally able to stop the war between Gaia and Guardian and saved a particular Akane Senri from being locked away in the City of Stone, he, who was nearing death due to rewriting himself too much, used his remaining lifespan to reach Kagari in the daisy hill. There, she stated that she finally found the good memory, but it came too late to stop Salvation. Kotarou was still able to stop it, but that meant killing her.
He passed away soon after, and in that spot in the daisy hill, a tree grew so high it looked like it was trying to reach the moon. Years later, Kotori, Chihaya, Shizuru, Akane, and Lucia summoned him as a familiar from the tree. He then bragged about being able to bring people outside the solar system if he is connected to thousands of people, but with the five girls, he could reach the moon.