The famous monk Eisai, who introduced Zen Buddhism to Japan, stayed at Seigan-ji before his second journey to China. The only surviving document written in his own hand describes this temple's founding and is a National Treasure.

At its peak, Seigan-ji controlled over 1,800 cho of land and had 42 sub-temples, making it one of the most powerful temples in the region when Imazu was an important port that rivaled Hakata.

The garden's centerpiece features jagged rocks arranged to form a turtle with a lone pine tree on top representing a crane—a traditional symbol of longevity in Japanese culture, surrounded by a 'lake' of green moss.

The temple's karesansui garden uniquely uses moss instead of gravel to represent water, and after heavy rains, it transforms into an actual pond thanks to ancient wells designed to channel water through the garden.