Hatoful Boyfriend Wiki

Hiyoko's Cave is a cave located in the outskirts of Littledove Hachiman City. It does not offer much protection from the cold, but it does have a doorbell for visitors to alert Hiyoko (despite there being no door at all). She is able to cook inside the cave, but usually only makes udon.

Carve it into your soul, kid!
Spoilers for Hatoful Boyfriend follow.

Sakuya Le Bel Shirogane moves into the cave with Hiyoko during his route after his father kicks him out for wanting to pursue music.

Spoilers end here.