What is the Chinese equivalent of a samurai?

When Japan centralized during the Edo period, for example, the samurai essentially became analogous to the Chinese shi scholar-officials, and (say) sixteenth century European warfare isn’t exactly known for its heavy reliance on feudal, martial aristocracies.

Is a Ninja Japanese or Chinese?

A ninja (忍者, Japanese pronunciation: [ɲiꜜɲdʑa]) or shinobi (忍び, [ɕinobi]) was a covert agent or mercenary in feudal Japan. The functions of a ninja included reconnaissance, espionage, infiltration, deception, ambush, bodyguarding and their fighting skills in martial arts, including ninjutsu.