The anime is based on a manga by the same name, by  Daisuke Yui. The series was published in 2012 and is still ongoing.Read the synopsis after the break.

After many years of dormant rest, a hot springs fairy awakens in modern-day Japan. However, while she slept, she took on the appearance of a young girl. She decides to cooperate with the locals whilst trying to regain her powers.

~^.^

Photo Credit: Onsen Yōsei Hakone-chan, Asahi Production, Production Reed Co., Ltd.