‘I still don’t get it.’ Fuka slowly shook her head. ‘But I have heard the term parallel worlds.’ They’d been using the English words, and now she gave the Japanese equivalent.

Kokoro repeated the Japanese characters to herself, and now she could picture it better.

She pictured the grand foyer of the castle. And parallel light radiating out from the seven mirrors side by side. The lights of each of the worlds beyond the mirrors never intersected.

Fuka said: ‘That idea was in a manga I read once. In the story there were as many parallel worlds as there were choices, and the main character had a kind of reunion of all his possible selves from those worlds. There were a lot of selves in all kinds of worlds, as many as the choices in his life – like what life would be like if he’d married his girlfriend, or if he’d stayed true to his dreams when he was young, and so on.’

‘Exactly! The number of choices is what I mean by the branches.’ Masamune nodded enthusiastically.

Fuka’s example made it a little easier for Kokoro to follow.

If only I’d done that, then reality would have turned out differently – that was something Kokoro thought about a lot. If only she hadn’t stayed away from school. If only she’d been in a different class from Miori Sanada. If only she hadn’t ever been a student at Yukishina No. 5 Junior High.

A hypothetical reality seemed preferable to present reality, and the more she fantasized about how great it would be if certain things could come true, the more reality that world seemed to take on.

‘And the branches of our parallel worlds are each of our stories. If you go by that example you gave, it’s as if I chose A, but if I’d chosen B it’d be a different world. In our worlds we each have a world where we exist, but each one’s slightly different.’

‘OK, but then – what about Ms Kitajima?’ Kokoro asked. ‘Aki said she’d never met her, but didn’t Masamune, Ureshino and I each meet Ms Kitajima? Doesn’t that mean Ms Kitajima exists in all our worlds?’

A doubt crept into her mind.

On that day, the only student Ms Kitajima had been told would be going into school was Kokoro. She didn’t seem to have been waiting for Masamune or Ureshino.

‘I guess the different worlds have some characters in common.’

Characters – the word made Kokoro bite her lip. Masamune was just continuing with the video game analogy, but the reality she was living started to feel to her as if it was all made up, like a miniature garden or something.

‘For instance, Aki and Subaru have never actually heard of the Free School, have they? So of course they’ve never met Ms Kitajima.’

‘Right.’

‘Yeah.’