Samurai in Japan's feudal era fought in various conflicts against different opponents. The specific adversaries of samurai depended on the period and the regional conflicts taking place at the time. Here are some notable opponents samurai faced:

1. Other Samurai Clans: Feudal Japan was characterized by frequent civil wars and power struggles among different samurai clans. Samurai often engaged in battles against rival clans and daimyo (feudal lords) to expand their territory or protect their interests.
2. Rebels and Bandits: Samurai were responsible for maintaining law and order within their domains. They often confronted rebellious factions, bandit groups, or local uprisings that threatened stability and the authority of the ruling class.
3. Foreign Forces: Samurai occasionally faced external threats from foreign invaders or rival clans from other regions of Japan. Notable conflicts include the Mongol invasions in the 13th century, during which samurai fought against Mongol forces attempting to invade Japan.
4. Ronin: Ronin refers to samurai without a master or lord. These masterless samurai sometimes formed groups or sought employment under different daimyo or engaged in freelance mercenary work. Ronin could pose a challenge to established samurai clans or become involved in conflicts with other factions.
5. Imperial Forces: During the Sengoku period, samurai loyal to the Ashikaga shogunate and the Imperial Court clashed in battles for control over the country. These conflicts often involved large-scale warfare between different factions supporting different claimants to the imperial throne.

It's important to note that samurai also had a code of conduct known as bushido, which emphasized principles such as loyalty, honor, and self-discipline. The conflicts they engaged in were not solely about personal gain but often driven by obligations to their lords, loyalty to their clans, or the pursuit of broader political objectives.