Photo by Mutimaro, via Wikimedia Commons (CC BY-SA 3.0)
🇯🇵 Japan · Miyagi Prefecture, Tohoku
Photo by Mutimaro, via Wikimedia Commons (CC BY-SA 3.0)
🇯🇵 Japan · Miyagi Prefecture, Tohoku
♨ Temperature
45°C
⛰ Altitude
120 m
⚗ pH
7.3
💧 TDS
1420 mg/L
🌊 Flow rate
abundant (multiple sources)
📅 Established
Kofun period (c. 531-570 CE)
✓ Verified on 2026-07-22
Akiu Onsen lies in the forested upper valley of the Natori River, approximately 30 kilometres southwest of central Sendai in Miyagi Prefecture, Tohoku. Known in antiquity as Natori no Miyu (the Honoured Bath of Natori), the spring was designated one of Japan's three imperial hot springs during the Kofun period (c. 531–570 CE), when Emperor Kensai reportedly used it to treat a skin condition. This designation placed Akiu alongside Arima and Shirahama as the oldest imperially recognized therapeutic waters in Japan. The spring appears in multiple classical poetry collections — the Kokinshu, Shin-Kokinshu, Shuishu, and Yamato Monogatari — making it one of the most literary onsen in Japanese history. During the Sengoku period, the warlord Date Masamune, founder of Sendai domain, was a devoted patron of Akiu. The water is a sodium chloride-bromide type: saline, warming, and noted for its high bromide content, which contributes to the deeply relaxing effect characteristic of the baths. The resort today accommodates visitors in a cluster of ryokans and large resort hotels, including the historic Sakan inn which has operated on the same site for over a thousand years. The surrounding Akiu Great Falls (Akiu Otaki) and the Rairaikyo gorge are designated scenic areas within the greater Sendai tourism zone.
| Sodium | 385 mg/L |
| Chloride | 510 mg/L |
| Bromide | 4.8 mg/L |
| Calcium | 98 mg/L |
| Sulfate | 142 mg/L |
| Bicarbonate | 88 mg/L |
Akiu Onsen holds the rare distinction of being one of Japan's three imperially designated hot springs from the Kofun period, alongside Arima Onsen (Hyogo) and Shirahama Onsen (Wakayama). Its presence in four classical poetry anthologies — Kokinshu, Shin-Kokinshu, Shuishu, and Yamato Monogatari — makes it one of the most extensively documented onsen in Japanese literary history. The Sakan ryokan, the oldest operating inn at Akiu, traces its lineage over one thousand years. The nearby Akiu Great Falls are designated a Natural Monument of Miyagi Prefecture.
Date Masamune (1567–1636), the 'One-Eyed Dragon' warlord who founded Sendai, used Akiu Onsen as his personal recuperation retreat. His patronage defined the cultural status of Akiu during the Edo period and established the ryokan tradition that continues today. The spring's appearance in the Kokinshu — Japan's first imperial poetry anthology (905 CE) — placed it within the highest tier of cultural landscape in classical Japan, where onsen were understood as sacred gifts of the land rather than merely therapeutic facilities.
The Akiu Onsen Ryokan Association manages spring allocation across member establishments and coordinates with Sendai City on visitor access to the surrounding Natori River valley. The Akiu Otaki waterfall and Rairaikyo gorge are managed as protected natural landscapes with controlled access. The association promotes the Sendai–Akiu connection via public transport to reduce car traffic in the valley.
Phone+81-22-398-2230
Websiteakiuonsenkumiai.com
AddressAkiu Onsen, Akiu-machi, Miyagino Ward, Sendai City, Miyagi Prefecture 982-0242, Japan