Complex sentence: Third son of the Yagyu family who serves as swordsmaster to the Shogun's family, having acquired a mastery of the Yagyuu swordsmanship sect and is in charge of espionage.
Split into simpler sentences: Third son of the Yagyu family who serves as swordsmaster to the Shogun's family. He has acquired mastery of a Yagyuu swordsmanship sect and is in charge of espionage.