Himiko closed the diary.
The bottom half of Entry #13
had been ripped our
Entries #8-12 wasn't even in the book.
The rest was all just
___white space.___
"It's no use..."
Aside from learning about 'Nikki,'
there was almost no information
she learned about
what happened to Koutarou.
It didn't even address any new information.
Even so,
she was glad.
It means that:
Koutarou...
had trusted
her
to keep
his
secret.