Thank God. I breathed a sigh of relief. I was nervous about Yuni, who could no longer play, sitting at the piano and striking the keys. My heart was in my mouth whenever I was in her company.

Kazune nodded. ‘Yes, it does. It’s perfect.’ She too was smiling.

At this moment, I couldn’t tell the difference between them.

‘Kazune, the thing is’ – Yuni’s voice was cheerful – ‘you can play fantastically well wherever you are.’

Yuni stood up and the two girls now exchanged places without fuss. Kazune spread out her sheet music on the stand and sat down. Just as Yuni had done, she struck a key with her finger. This must have been the standard A above middle C, but I could immediately picture scenery opening out before me, with a path extending through a crisp, silvery forest. A young deer seemed to frolic in a hidden glade.

Yuni gazed up at me, her face beaming. ‘It sounds like the splashing of clear water.’

I was struck by how the same sound could conjure up entirely different images, depending on the person listening.

‘I used this particular sound as the foundation for the entire tone and colour,’ I explained, and Kazune nodded again.

She returned her hands to her lap for a moment, then slowly began to play her piece. It started so naturally I had no time to gather myself – as though she’d quietly latched on to music drifting about in the ether, and was channelling it for us through the piano. Her hands were sure and confident as they moved up and down the run of the keys, never faltering. When Kazune played, everything seemed heightened in its reality, as if the piano and the music had a life of their own.

Leisurely enough at the start, by halfway through the piece the sound was utterly sublime, with the notes lingering in the air like a cascade of sparkling gemstones, stretching as they emerged before fading away, as pure as can be, each tone in perfect harmony with the rest.

‘It’s completely different from when she practised at home,’ Yuni said excitedly. ‘So this is what you can do – to make it sound like this!’ Face flushed, she turned to me. ‘You are amazing, Mr Tomura. I can’t wait to start learning how to tune. I want to be your apprentice.’

I fell silent. Whaat?

My voice was off-key. ‘The amazing person here isn’t me, it’s Kazune.’

She had sounded out the possibilities at first, and now the instrument belonged to her. Just as Yuni had said, Kazune could adjust to playing any piano.

‘Not at all – it’s the tone of this piano pulling her along. Kazune’s riding it, enjoying herself, drawing out sounds she’s never dreamed of before.’