Miharashi Park is a park that spreads across Hakodate City and is a place of relaxation for the citizens. It is home to the nationally designated Place of Scenic Beauty, the Former Iwafune Family Garden (commonly known as Kosetsuen). This garden was built from the Meiji to Taisho eras on a vast site of about 13 hectares, and is the only nationally designated cultural property garden still standing in Hokkaido. It is said that a gardener invited from Kyoto was involved in the garden's creation, and his skills and aesthetic sense can be felt everywhere. It is a stroll-style garden with a pond, and you can enjoy the quaint scenery while walking around the garden path centered around the pond.

In particular, the garden's pavilion, Kikugetsutei, is a valuable building built in the Meiji era and designated as an Important Cultural Property of Japan.

Kosetsuen is especially known as a famous spot for viewing autumn leaves. Every year from late October to early November, about 150 species of trees turn brilliant colors, and the entire park is enveloped in a brocade look. During this time, the Hakodate MOMI-G Festival is held, and the 100-meter-long avenue of maple trees is fantastically lit up. The autumn leaves that stand out against the darkness of night have a fantastic beauty that is different from that of the daytime, and they captivate many visitors.

Within the garden, there is also a Green Center where you can learn about the garden's history and plants, as well as a Garden Pavilion that can be used as a rest area.