Have you heard of the park in Ōe Town, Yamagata, known as “Japan’s Number One Park”?
From its observation deck, you can overlook the majestic Mogami River and the beautiful townscape of Ōe, with breathtaking scenery spreading out before you.
This time, I visited Japan’s Number One Park (Aterazawa Tateyama Castle Historic Park) in person, and I’ll share a detailed report—with photos—of its stunning views and highlights within the park!

What Is “Japan’s Number One Park”?

Located in Aterazawa, Ōe Town, Japan’s Number One Park (official name: Aterazawa Tateyama Castle Historic Park) is a nationally designated historic site built on the remains of a mountain castle.
It offers a sweeping view of the Mogami River as it curves dramatically, along with a grand panorama of the Asahi Mountain Range, Mount Zao, and the townscape of Aterazawa. Its scenery is often described as “Japan’s best view,” making it a popular spot among photographers and travelers.

Selected as One of the “Japan Top 100 Walking Trails”

The park is also listed as a Mogami River Viewpoint and one of the Japan Top 100 Walking Trails, allowing visitors to enjoy seasonal beauty such as cherry blossoms in spring and vibrant foliage in autumn.

To the east lies the wide Murayama Basin, while to the west stretch the Asahi Mountains and Mount Zao. The dynamic landscape—where town, river, and mountains blend together—creates a truly impressive scene.

Stunning Views from the Observation Deck: On‑Site Report

I had always wondered why Aterazawa Tateyama Castle Historic Park is nicknamed “Japan’s Number One Park.” But once I saw the view for myself, the name made perfect sense—the scenery is truly exceptional.

The peaceful townscape of Aterazawa spreading along the right bank of the Mogami River was especially memorable. It’s the kind of view that makes you want to stay longer and simply gaze at the landscape, making it an ideal spot for those who want to enjoy nature quietly.

A Monument to the Mogami River Boat Song at the Summit

At the summit, a large monument dedicated to the Mogami River Boat Song stands proudly.

The inscription explains that the Mogami River Boat Song originated in Ōe Town (Aterazawa) and was nurtured through cultural exchanges along the Mogami River’s river transport routes.

The Mogami River Boat Song

The Mogami River Boat Song was originally sung as a work song by boatmen, carrying wishes for safe river travel. Later, thanks to the efforts of local volunteers and folk musicians, the song was refined and developed, and by the Showa era, preservation and promotion activities had spread nationwide—eventually making it a well‑known folk song throughout Japan.

This monument was erected to commemorate those achievements.

There is also a rest area donated by the local Rotary Club, allowing visitors to sit down and enjoy the scenery at a relaxed pace.

Strolling Through the Historic Mountain Castle Ruins

Japan’s Number One Park is built on the site of the Aterazawa Tateyama Castle ruins. The castle was constructed around the 14th century and served as an important strategic point controlling river transport and travel along the Mogami River. During the Sengoku period, it came under the rule of Mogami Yoshiaki, and was abandoned in the early Edo period.

Today, remnants such as dry moats, earthen embankments, and kuruwa (flat terrace areas) still remain, allowing visitors to imagine what a medieval mountain castle once looked like as they explore the grounds.

Enjoying the Scenic View Toward Mount Hayama

From the summit, you can enjoy a sweeping view of Mount Hayama and the surrounding mountains. It’s a peaceful spot where you can take your time, relax, and simply enjoy the scenery.

Facilities Available at Japan’s Number One Park

The park is equipped with rest areas and restrooms, making it easy to visit even with children (restrooms are closed during winter). The grounds are spacious, so it’s also a pleasant place for a casual walk.

Nearby: Yamagata Asahi Youth Nature House

Located nearby, the Yamagata Asahi Youth Nature House is a facility where children can grow through hands‑on activities in nature. It is used for overnight learning programs, camping, outdoor cooking, and other activities that help foster cooperation and independence.

How to Access Japan’s Number One Park (Aterazawa Tateyama Castle Historic Park)

Japan’s Number One Park is about a 20‑minute drive from the Sagae Interchange on the Yamagata Expressway. There is a parking area at the entrance of the park, and from there, visitors walk along a narrow path to reach the main grounds.

Restrooms are available, but they are closed during the winter season.
Access may also be restricted in winter depending on road conditions, so be sure to check the latest information before visiting.

Summary

Japan’s Number One Park truly lives up to its name, offering breathtaking scenery that can be enjoyed year-round.
Standing before the dramatic curve of the Mogami River, you’ll be overwhelmed by a sense of scale and beauty that photos simply cannot capture.

The park is also a familiar destination for local elementary school students on field trips, and the nearby Yamagata Asahi Youth Nature House is cherished as a place where children build friendships through camping and outdoor activities.

With the historic Aterazawa Tateyama Castle ruins adding a touch of history, visitors can enjoy not only the views but also a pleasant walk through the remains of a medieval mountain castle. It’s a spot well worth visiting at least once.Restrooms are available, but they are closed during the winter season. Access may also be restricted in winter depending on road conditions, so be sure to check the latest information before visiting.