Sakura uses it to avoid going back to the Matou's

Almost frantic, Sakura took a pencil out of her bag and opened the notebook. Putting the pencil to the page she wrote:

Shirou Emiya will hurry to find Sakura and invite her to stay at his house for the night. Once there, he will offer to let her sleep in his room. He will be happy to engage in any sexual activities Sakura suggests.

After writing that, Sakura snapped back to her senses. That's right, she thought. There's no way this notebook could do anything like that.

Sakura closed the notebook. For a moment, she considered just leaving it on the street, but she decided to take it home. I'll throw it out when I get home, she told herself, but deep down she knew she wouldn't. This was the only way she could make her dreams of being with Shirou closer to being real.

She put the book in her bag and started for "home".

A few moments later, she heard what sounded like rushed footsteps behind her. Looking back, she saw Shirou running towards her. Sakura stopped, her mouth almost a gap.

"Sakura!" Shirou called out as he drew near.

"What is it sempai?" Sakura asked.

"I was thinking," Shirou began. "You've been helping me with a lot of the household chores for a while." He seemed to be a little nervous. "So I was wondering if you would like to stay at my place for tonight?"

Sakura couldn't believe what she was hearing. Sure, Shirou was a very nice person, but he wouldn't ask her to stay the night at his place unless it was because of the weather. Was it the notebook?

"Thank you, sempai. I would like that," Sakura happily answered as she turned around to follow Shirou back to his house.