Yup, that's a Torii. It marks the symbolic entrance to a shinto shrine. So maybe there's a miko around to give the yukkury some 'easy time' with her mister broom.
This pic also reminds me that I have to play more Nobi-Nobi-Boy again...
(right): Koreimu: "Weimu'j gwood ach stwetch-stwetch choo!" Komarisa: "Yuyu~n! Weimu can weally chake ich eajy!" Koreimu: "Bwig shish Mawisha can stwetch-stwetch weally weally high!"