This is basically like a summary of what'd be happening, in case you're too lazy or uninterested in reading the actual chapters.
Name: Ikari Tokisaki.
Status: Alive.
Race: Human (Currently).
Age: 18 years.
Affiliation:
• Tokisaki Family.
• Unnamed Academy.
• Unnamed Town.
Relatives:
• Unnamed Parents.
• Tokisaki Kurumi (Sister)
• Sawa Yamauchi (Friend)
BACKGROUND.
A normal—albeit not normal teenager with the memories of another world which views his current world as a fictional one.
Greatly attached to his little sister even from a young age, but despite this, he keeps a certain distance away from her.
However, upon learning of this world, he began to fear for her life.
HISTORY.
Ikari is first seen waking up after seeing memories from another world.
He is woken up by Kurumi who is also his sister. After a brief moment, he joins her for breakfast.
Some time had passed since then, and the second prelude shows how Ikari has mixed feelings about Kurumi's sense of justice.
As this is what made her what she is.
He is shown being pragmatic to what Kurumi feels, even stating to her that even God can't save humanity himself.
But the next scene would then show him saving a cat from atop a tree.
Prelude III sho3s Ikari leaves Kurumi with Sawa to run an errand which he would later realise was his mistake.
Feeling something was off, Ikari bolted off to find Kurumi, calling Sawa who confirmed Kurumi had left her side shortly after.
He would later have a brief encounter with someone he'd have a short talk with.
After that short talk, he'd then begin to stop hesitating in making choices.
⸻
Name: Kurumi Tokisaki.
Status: Alive.
Race:
• Human (Formerly).
• Spirit (Currently).
Age: 17 years.
Affiliation:
• Tokisaki Family.
• Unnamed Academy.
• Unnamed Town.
Relatives:
• Unnamed Parents.
• Tokisaki Ikari (Brother) (Crush)
• Sawa Yamauchi (Friend) (Rival in love)
BACKGROUND.
Little sister of Ikari Tokisaki. But not the one that had descended into her psychopathic self we all come to know.
She's but a kind girl who genuinely can't bear to see others suffer. She believes the world is not so rotten that it can't be saved.
Even though her brother doesn't hold the same beliefs as her, she still believes so.
HISTORY.
First appears in Prelude I waking Ikari up and would then go to prepare breakfast for him.
They both live alone and this is thanks to Ikari persuading his parents, she had learned so naturally from him.
In prelude II, she is also shown to feel sympathy for those suffering. The trio will then pass by a park where Ikari would help a kitten stuck on a tree.
The following event of what happens in Prelude III can be found in its chapter.
⸻
Name: Yamauchi Sawa.
Status: Alive.
Race:
• Human (Currently).
Age: 17 years.
Affiliation:
• Unnamed Academy.
• Unnamed Town.
Relatives:
• Unnamed Parents.
• Tokisaki Ikari (Friend) (Crush)
• Tokisaki Kurumi (Childhood Friend) (Rival in love)
BACKGROUND.
Tba.
⸻
So, something I noted when reading the LN was that Kurumi is technically older than her physical age.
Though the author didn't specify, but I'd say quite some time passed after the tragedy had happened to her.
Beside that, she was in another city and would only come to Tengu City, after meeting with [Phantom].