Board Thread:Questions and Answers/@comment-24578352-20140222115623/@comment-8472350-20140222191028

It was expanded on in the anime, but here's the page it happens on in the Manga:

http://mangafox.me/manga/saki/v09/c074/11.html

Oohoshi-san may be a captain, but she was still in the building when Jindai-san fell asleep; presumably, Oohoshi-san, like Saki and Amae, have the same sensory capability of finding other monsters.