ES CON FIELD HOKKAIDO

Completed in 2023 in Kitahiroshima City, Hokkaido, ES CON FIELD HOKKAIDO is the home ballpark of the Japanese professional baseball team Hokkaido Nippon-Ham Fighters. Its three-tier spectator stands can accommodate about 35,000 people. Giving top priority to harmony with the surrounding environment, the design blends into the locality with features such as a large gable roof, characteristic of Hokkaido, and multiple terraces along the stadium's middle floors.

We created Japan's first ballpark with a retractable roof and a natural-grass playing field—the largest retractable roof in the world. The fresh scent and vivid green of the turf create a soothing atmosphere for spectators. Designed to delight all five senses, the ballpark puts the comfort of both players and fans first.

The design process below explores how we gave shape to the concept of "building a ballpark the world has never seen before."

The Large Gable Roof: Design that Carries on Hokkaido's Cultural Traditions
An Asymmetrical, Bowl-Shaped Stadium—Uncommon in Japan
Japan's First Natural-Grass Ballpark with a Retractable Roof
Simulation of Batted Ball Trajectories
One of the Most Spacious Team Facilities in the World, Totaling Approximately 3,400 m²
Community Development with the Ballpark at Its Core
Structural Planning to Operate a Retractable Roof Weighing Approximately 10,000 t
Construction without Precedent

The Large Gable Roof: Design that Carries on Hokkaido's Cultural Traditions

In exploring designs for the new ballpark, we incorporated the culture, natural features, and other aspects of Hokkaido and Japan while leveraging expertise from Major League Baseball stadiums. After thoroughly identifying the site's culture and conditions, we adopted an exterior defined by a prominent gable roof—familiar across Hokkaido. With brick-toned tiles on the outer walls, the ballpark aims to become a new landmark for the region.

The gable roof—able to withstand harsh natural conditions—was incorporated into the design. (Photo of facility at Farm No. 2 of the former Sapporo Agricultural College, now Hokkaido University)

An Asymmetrical, Bowl-Shaped Stadium—Uncommon in Japan

The stadium's layout is asymmetrical: the home-team area (right) is designed to hold as many seats as possible, while the visiting-team area (left) features amenities including a hotel and sauna on the upper levels. (Photograph: Kawasumi·Kobayashi Kenji Photograph Office)

The ballpark adopts an asymmetrical layout: the home‑team side (right field) maximizes seating, while the visiting‑team side (left field) houses upper‑level amenities such as a hotel and sauna. This plan is uncommon among ballparks in Japan.

Sketch of envisioned playing field at the initial planning stage in 2018

Drone aerial photograph at completion in 2023

Spectator stands wrap 360° around the field in a bowl-shaped cross-section, offering clear sightlines from every seat. To bring spectators closer and enhance unity and immersion, the riser height is 31 cm per row in the lower tiers (two 15.5‑cm steps) and 49.5 cm per row in the upper tiers (three 16.5‑cm steps). We verified riser and tread dimensions with a program built in 3D modeling software, optimizing for sightlines and constructability.

Verification of spectator sightlines using sectional drawings

Japan's First Natural-Grass Ballpark with a Retractable Roof

About 7,600 m² (combined infield and outfield) is covered in natural grass cultivated exclusively for ES CON FIELD HOKKAIDO for two and a half years. (Photograph: Kawasumi·Kobayashi Kenji Photograph Office)

ES CON FIELD HOKKAIDO is the first ballpark with a retractable roof to feature a natural grass playing field. To cultivate natural grass in Hokkaido's snowy, cold climate, we adopted a retractable roof and created a glass wall along the southeast side to admit sunlight and wind. Before finalizing the design, we verified a full range of factors to optimize grass photosynthesis and respiration.

We built six 1:30 scale mock‑ups, matched for factors including orientation and grass species, and spent about two years testing cold-climate cultivation.
Beneath the field, pipes circulate cold water in the summer and warm water in the winter to maintain the optimal turf temperature year-round.
A wind tunnel at the base of the glass wall admits natural wind; simulations identified circulation suited to turf growth.

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Simulation of Batted Ball Trajectories

We analyzed data for roughly 15,000 batted balls (speed, direction, angle, and distance) from 2016 to 2019. By accounting for drag and spin, we estimated landing points under conditions specific to ES CON FIELD HOKKAIDO.

For spectator safety, we studied the size, shape, and specifications of protective netting and assessed materials such as glass in areas subject to impact. To balance sightlines and safety behind home plate, we prioritized stopping the majority of high‑risk, high-impact balls rather than addressing those that pose less danger, and therefore installed protective netting about 20 m high.

One of the Most Spacious Team Facilities in the World, Totaling Approximately 3,400 m²

Locker room designed with player input; a circular plan heightens team unity. Lighting presets support both relaxation and pre‑game focus. (Photograph: Koichi Torimura Photograph Office, 2023)

Totaling approximately 3,400 m², the team area ranks among the world's largest—even compared with Major League teams. The weight room, trainers' room, and related facilities are arranged for efficient movement by players, managers, and staff so they can perform at their best.

Community Development with the Ballpark at Its Core

(Photograph: Kawasumi·Kobayashi Kenji Photograph Office)

The broader district encompassing ES CON FIELD HOKKAIDO—Hokkaido Ballpark F Village—was planned as a space for co-creation, where fans, partner companies, and local residents join hands to energize the community and contribute to society. With the ballpark's opening in Spring 2023, partners launched diverse services and facilities: a villa resort, senior housing, glamping, early childhood education and care center, restaurants, an agricultural learning facility, a kids' play area, and dog runs. Although a professional baseball season hosts only around 80 home games, ballpark‑centered community development has established a creative public realm that attracts people of all ages and nationalities even on non-game days.

Sketches of the envisioned town development at the initial planning stage in 2018

Study models of envisioned town development at the initial planning stage in 2018

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Structural Planning to Operate a Retractable Roof Weighing Approximately 10,000 t

Inside the ballpark with the retractable roof fully closed (Photograph: Kawasumi·Kobayashi Kenji Photograph Office)

With a horizontal projected area of approximately 25,000 m² and a span of 167 m, the roof is one of the largest of its kind. Twelve one-directional truss beams form the main frame supporting the roof, which weighs approximately 10,000 t. The roof travels 132 m along track girders to open or close in about 25 minutes. Each end of the trusses is supported by bogies—24 in total—that move slowly across the structure.

The glass-wall structure on the ballpark's southeast side is designed to admit abundant sunlight for turf growth. A steel frame supports both the glass wall—reaching 70 m at its highest—and the roof.

The glass-wall structure—whose columns incline to meet in a V at the base—ensures design quality and accessibility. Opening the large doors below the eaves turns the ground-level concourse into a wide-open space that blends into the Sawa Area. (Photograph: Kawasumi·Kobayashi Kenji Photograph Office)

Construction without Precedent

Using the sliding construction method, sections of the roof were built on temporary support columns called bents, then slid into place.

The glass wall has over 1,000 glass panels.

The ballpark had to be delivered in 32 months while tackling a broad range of challenges: its unprecedented shape, the large retractable roof and expansive glass wall, natural grass, the impact of the COVID-19 pandemic, and the snow and low temperatures of Hokkaido's harsh winters. We were able to complete ES CON FIELD HOKKAIDO thanks to the efforts of over 600,000 people in total who supported us in pressing forward with construction and overcoming many difficulties.