Her grandfather seals the well. Kagome changes into something less bloodstained. Ayako fusses over her injuries while Kagome draws a map of the past for Sota, going over the main events - here was the well, and here was the sacred tree, where the half-demon boy was pinned by a magic arrow. Here's about where the village was, in relation to both of them, and here's the path she took through the forest to the river that Inuyasha fell in, where a river still runs today. Here's the place where the bandits took her, and the path that she and Inuyasha took back to the village to kill the crow demon.
It's a lot of adventure, for a day and a half. Enough adventure for anyone, surely. Ayako tells her that everyone ought to have one such youthful adventure, and she's lucky that hers did no damage to anyone. She believes her, now, though she didn't at first. The well is sealed, and no threat to their ordinary lives. They can afford to believe.
Kagome takes a walk outside, as the sun sets and Ayako cooks Kagome's birthday dinner, one day late. She spends a long time looking up through the branches of the sacred tree. Off to one side, easily missed, the very end of an arrow shaft sticks about an inch out of the tree, as if the rest was subsumed long ago, as the tree grew. Kagome remembers that one of the villagers had shot an arrow at her, the first time they saw her with Inuyasha, back when he was still asleep, and the arrow had stuck in the tree. She pulled the magic one out, but the other remained. Since long before Kagome was born, the tree has been growing around it, erasing the only other evidence of Kagome's adventure.
In a few centuries, the tree will subsume the arrow completely, leaving it impossible to see that the tree was ever struck. Kagome's injuries will heal up in mere weeks, and there will be no evidence but her word that she was ever hurt, either. Even if it is remembered, in some form, it won't be distinguishable from legend. It won't matter whether anyone believes it; the ripples will have left the world long ago.
It's only been hours, not years, and the realness of it all is already fading, at least when she's in her living room with her family. It's different under the tree, though. Here, she feels connected to the past and to her ancestors, to a long line of Higurashis who have guarded and maintained this shrine for generations.
Except for her.
Kagome is not strong, or knowledgeable, or brilliant, or wise. Maybe she has some special powers hiding in her, but they mostly don't seem very useful. And yet - the jewel this shrine once contained was entrusted to her. Not by Kaede, but by her very flesh and blood. She doesn't understand it, but the jewel was a part of her; she was meant to have it, and to keep it safe. And when the time came to stand up and accept the responsibility that she alone had been entrusted with, Kagome refused. She had said to let someone else do it, not knowing whether anyone else could, either.
That is what she turned her back on. Not some youthful adventure, to be dipped into and grown out of. Her ancestral obligations. Her past. Her future. Her destiny. Her very purpose.
If all the darkness that she unleashed on her ancestors has been eroded by time, does that make it any less real? If a hundred Mistress Centipedes destroyed a hundred villages, and then the world forget about them completely, is there any sense in which the forgetting means that the crime, the cowardice, the desertion of her duty was not, in fact, a betrayal of all of those people, who when they lived were as real as she is now?
She thinks about the girl she was, for a day and a half. It's easier, with four hundred years of distance, not to hate her. Maybe she screwed up, but she was the sort of person who could have grown into someone impressive. She saved the life of someone who had kidnapped her. The trick with the arrow was disastrous, but it was the kind of mistake that you could imagine a hero out of legend making, not something that an ordinary person would do. But a hero would have spent years, or decades, cleaning up a second's mistake. They wouldn't have shrugged and gone home.