Improve water and sediment quality by using the wrecked and abandoned former eel-raising ponds around Lake Hamanako for the planting of northern mangroves, then selecting and planting cold-resistant stock in areas of brackish water. This will help in the restoration of the environment around Lake Hamanako, while aiding the aquaculture of the mangrove crab (which is now rare, but used to be found in the mangrove tidal flats and is a native to Lake Hamanako) to boost its numbers as a resource. Specifically, this project will restore and use the abandoned eel-raising houses, to product mangrove seedlings and raise young crabs. It will promote aquaculture that is compatible with environmental conservation, and will create a new tourism resource.