The Nagai River is a river located in Japan, primarily flowing through the Osaka Prefecture. It is known for its scenic beauty and plays a vital role in the local ecosystem. The river is approximately 30 kilometers long and is a tributary of the Yodo River, which eventually flows into Osaka Bay. The Nagai River is surrounded by parks and recreational areas, making it a popular spot for outdoor activities such as walking, cycling, and fishing. Its banks are lined with cherry blossom trees, attracting visitors during the spring season when the flowers bloom.