Hi, Duck of Death12 ( lol, nice name ) Everyone gets at least 3 companions from MooShu. Monkey King - direct quest line, Ju Hao from a side quest in Sacred Mountain ( look for Yagi, she's in a temple near the shrine.) & Shiruku Neko from side quest given by the constable in Subata Temple. Also each class gets a companion from side quests. Good Luck!
Actually, there are two side quests in the whole of Mooshu that reward companions. One of them, you must go to Constable Shao, in Subata temple. If you look around, you will find him easily. That quest grants Shiruku Neko, also known as the cat ninja. For the second quest, you must find Yagi Sonada, in the temple of the south wind. If i can remember correctly, she is in a house area away from the center of the temple. That quest grants Ju Hao, the inoshishi chief. These are commonly overlooked quests, so don't get discouraged if you don't find them easily.
There are two quests that will become available near the conclusion of the Mooshu storyline, Ju Hao and Shiruku Neko are companions that are available after completing storyline quests in Subata Skyway, you can get them some time after obtaining Monkey King. Just accept all sidequests and you should be fine! Note that some sidequests are available in other areas after completing a storyline quest in a different area!