This study explores how Japanese development non‐governmental organizations (NGOs) had altered their patterns of advocacy and accountability after changes in political structure that occurred in the 2000s when the Democratic Party of Japan created the two‐party system and the Liberal Democratic Party took power again. After the 1990s, a unique feature of development NGOs actively performing advocacy and accountability within the ODA domain, while also eagerly reaching political authorities by forming networks, was found. Behind their efforts were the appearance and expansion of the Democratic Party of Japan through its systematic and political ties. As concluding remarks, the active participation of civil society not only represents the level of internal resources mobilized within the civil society network, but is also an indicator on how supportive the policy space at the bottom is towards civil society.