[...]

The night before Nii-san took me to the school, Senpai came home late at night with injuries. I checked his hand -- his Command Spells had vanished.

... When I asked where Saber-san had went, he said she'd gone home.

[Never mind what Sakura thinks she did or didn't see; both girls know the boy is absolutely terrible at lies, and thus his statement was as good as truth.]