NPB History | Belluna Dome — The Stadium Announced Before the Team Was Bought

The roof does not touch the stands. Walk the concourse at Tokorozawa and daylight comes in through a gap that runs the whole way round, along with the trees, the weather and the insects. This is a dome in name only: a cover was dropped over an open-air bowl years after the fact, and the sides were left open.

The sequence that produced it was unusual. In July 1978 the Seibu group announced it would rebuild Seibuen Stadium, a modest ground cut into the Sayama hills and used mostly by amateurs, into a large modern ballpark. Seibu owned no professional club at the time, and the announcement was read as exactly what it turned out to be. That October the shares of the struggling Crown Lighter Lions passed from their Fukuoka owners to Kokudo Keikaku, the group's land arm, and a team that had spent its whole existence in Kyushu was moved to Saitama. About 2.8 million people lived along the Seibu railway lines with no serious ballpark among them. Kamiigusa in Suginami, built for the professional game before the war, had closed in 1959.

Construction ran so late that no exhibition game was ever played here. The first fixture came on 14 April 1979 against Nippon-Ham, with former prime minister Takeo Fukuda throwing the ceremonial pitch; he had stood as go-between at the wedding of the owner, Yoshiaki Tsutsumi. Yoshiie Tachibana hit the new ground's first home run into the right-field seats in the opening inning, his first as a professional, and fireworks went up behind centre field. Then the fielders made seven errors and Seibu lost 1–7. That was already the team's sixth consecutive defeat of the season. The run reached twelve, and the first win of the Tokorozawa era did not arrive until the fifteenth game, against Nankai on 24 April.

Three seasons later the club won the first of the eight Japan Series titles it would take by 1992, five of them clinched on this field. Seibu announced the roof in 1996, though the idea was older: the floodlight towers had been built out on the perimeter rather than on the stands, so a cover could be added later without moving them. Tamako and Sayamako sit immediately north and the valley funnels rain. By 1999 the playing area had been recut to 100 metres down the lines and 122 to centre.

Come in August, when the ground has its worst reputation and its clearest explanation. Take a seat high on the third-base side and look at the gap between the roof and the stands.

Coordinates 35.768538, 139.420466 — the dome itself, on the site of the former Seibuen Stadium; ±20 m, OSM and Wikidata agree to about 5 m, pending on-site check.

Cover: the interior seen from behind home plate, the open gap between roof and stands visible along the far side, photographed by Tokoro_ten, public domain, via Wikimedia Commons.