OnsenDiary: Onsen & Bath Log

A hot-spring diary with a Spring Guide — collect Japan's nine therapeutic spring qualities by soaking in each one. Log every onsen with one photo, fully offline.

OnsenDiary is a hot-spring collection app built around a Spring Guide — an encyclopedia of the nine therapeutic spring qualities of Japan. It is not just a logger: you learn about each spring quality and collect them as you go.

• Spring Guide (the highlight): Simple, Chloride, Bicarbonate, Sulfate, Carbon dioxide, Iron, Sulfur, Acidic and Radioactive springs. Each entry has its traditional nickname ("the Bath of Beauty", "the Bath of Heat"), the character of the water, what it is traditionally known for, and a bathing tip. Actually soak in a spring quality to unlock its entry — aim to complete all nine.
• Register a spot with one photo; the address is suggested from your current location, fully on-device.
• Log each visit with spring-quality tags, a water-temperature note and a 5-star rating; earn visit and collection badges.
• Personal stats and calendar: weekly bar chart, onsen ranking and a monthly calendar.
• Private by design: no account, no login, no cloud.

Note: the Spring Guide is general cultural information about traditional onsen, not medical advice.

Perfect for onsen lovers, sento fans and travelers in Japan.