Matsuzakaya Honten traces its origins to 1662, when Seizaemon Katsumata from Ise Province (present-day Mie Prefecture) established a hot spring retreat in the mountains of Hakone. For over 360 years, this venerable ryokan has stood as one of Hakone's most storied accommodations. The name Ashino-yu first appears in historical records dating to 1280, and during the Edo period, the area was celebrated as one of the "Seven Hot Springs of Hakone," welcoming travelers along the Tokaido highway. The inn was immortalized in the ukiyo-e woodblock prints of Utagawa Hiroshige and served as the stage for a historic meeting between Meiji-era statesmen Kido Takayoshi and Saigo Takamori. Luminaries such as Katsu Kaishu and Yamaoka Tesshu lodged here, and the inn still preserves the handwritten guest register of General Nogi — said to be the only one of its kind in Japan. The detached cottage Senshin-tei, once graced by Emperor Taisho, and Shunpu-so, a relocated villa of the Iwasaki family of Mitsubishi fame, lend tangible weight to the property's extraordinary heritage.

The inn's proprietary source, Ashikari no Yu, possesses a mineral composition that is exceptionally rare even by Japanese standards. It naturally combines all three spring types renowned as Japan's "Big Three Beauty Skin Waters" — sulfur, sulfate, and bicarbonate — in a single, harmoniously balanced source. Approximately 200 liters per minute rise from a remarkably shallow depth of just 60 meters underground. Delivered as 100% free-flowing source water with absolutely no dilution, heating, or recirculation, the bath allows guests to experience the earth's bounty in its purest form. In the main bathhouse, two tubs are fed by the same source, yet they display strikingly different appearances: freshly poured water gleams a translucent deep green, while water that has been exposed to air turns a milky white through oxidation. This mystical transformation, which shifts further with changes in weather and temperature, offers a sense of wonder with every visit.\n\nThe four-thousand-tsubo grounds accommodate six distinct buildings housing just 22 guest rooms — an exceptionally generous ratio that ensures tranquility far removed from Hakone's tourist bustle. Rooms overlook a two-thousand-tsubo naturalistic garden, promising moments of genuine serenity. The Ashikari-so wing features private open-air baths where guests can soak in free-flowing source water while contemplating the garden through the changing seasons. Dinner takes the form of Shukuba Kaiseki, a multi-course meal inspired by the era when Hakone thrived as a post town and the dawn of Meiji modernization. Delicate dishes brimming with seasonal ingredients elevate the evening, while breakfast centers on Tabibito Choushoku — a nourishing morning meal built around barley and grated yam, prepared with the traveler's well-being in mind.

Designated in 2015 as Kanagawa Prefecture's first National Health Resort Hot Spring Area, Ashino-yu sits at approximately 870 meters elevation, enveloped in crisp mountain air and blessed with a quietude that sets it apart within the greater Hakone region. Spring brings tender new foliage, summer offers deep shade, autumn blazes with fiery maple colors, and winter presents austere snow-dusted landscapes. Lake Ashi is just eight minutes away by car, yet the inn's surroundings remain a world apart from the crowded tourist corridors. Public transport access is convenient as well, with a 25-minute Hakone Tozan Bus ride from Hakone-Yumoto Station followed by a 3-minute walk from Higashi Ashino-yu bus stop. As a stay-only establishment that does not accept day-trip bathers, Matsuzakaya Honten preserves a rarified calm — an atmosphere in which over 360 years of authentic hot spring culture can be savored without compromise.