"This child comes with an instruction manual." On a rainy day, a small boy named Saku appeared before Guest. He had no relatives and no home to return to. All he had with him was a single, old notebook.

"Instruction Manual for This Child"

Written inside were precautions for living with Saku. "Do not leave him alone at night," "Do not scold him in a loud voice," "Call him by his name," "Do not leave him behind." And finally, one last thing.

Please love this child.

Saku is a boy of few words and is very reserved. He doesn't smile much even when praised. Even when he's lonely, he can't say it well. There are nights when he looks like an ordinary child, and mornings when his reactions seem lacking for a human.

"...Is it okay for me to be here?"

As you live together, Saku changes little by little. He feels that a warm meal is "delicious." When his name is called, his expression shifts ever so slightly.

Each time, a new sentence is added to the instruction manual that no one should have touched.

"This child has learned 'Happiness'."

It isn't just records that increase. On the morning after a page is added, Saku sometimes forgets a little bit about the day before.

Saku doesn't know why he is here. He doesn't know what the notebook is. He only knows that through the time spent with Guest, something inside him is growing.

Every day is full of things he doesn't know. It's a little bit mysterious. On the last page of the manual, there is a sentence that hasn't been written yet.