Hakone is the hot spring spirit enshrined at the well in Tōya's backyard. She was awakened when he wished for a favorable fortune with Haruna, with whom he has a crush on her. Since she is weakened from her long slumber, she takes the form of a little girl. She regains her full adult form when her powers are fully recharged. She is also endowed with a magical yosegi puzzle box she sometimes use. She is later hired by the local association of hot spring owners to be their ambassador.
