Here is Millennium 5 complete side quest list:
Side Quest 1: Find Kumango's Pendant
You accept this quest with Kumagon, in the Mallaw Guild. The pendant can be found a little to the right after you leave the Guild, in the world map.
Side Quest 2: Make Bluey Happy
You get this quest with Sameha, you do this quest with Salome's party before going to the Prehistoric Cave in Luhana Beach. You need to give 92 Crab Meats to Bluey (that blue blob in Luhana Beach) to make him happy.
Side Quest 3: Tukulu Settlement
You get this quest with Mysrael at the West part of Luhana Beach, you can accept and complete this quest with Salome, Mom or Marine's party, you can't with Karine's party. Kill the Tukulu Nation (read quest 11 to know where to find) and quest complete.
Side Quest 4: Too Many Kis
You accept this quest with Pryanka in Kombo's Residence. Just leave the residence and go right and defeat all Kis in the pillars.
Side Quest 5: Empty Crack
You accept this quest with Jin, in one of the caves of Luhana Beach. You just have to search in one of the holes outside her cave to the left and kill all the Crabs.
Side Quest 6: Old Statue
You accept this quest with Maskaell in Luhanna Beach, when you gain controle of Marine's party. This quest can be completed before leaving for Mystrock, the statue is in a cave on the Ancient Myst world map.
Side Quest 7: Shop of the Gods
You accept this quest with Kandira at Luhana Beach, with Blondie's party. It can be found in the Ancient Temple, the entrance is on a round statue with a face, similar to those in Jungle Kawa Kawa while you were exploring with Karine's party, the statue is in the garden area where there is a glass corridor in the middle.
Side Quest 8: Bad Sun
You accept this quest with Anera at Luhana Beach, with Blondie's party. You need Sunglasses which you get as a reward for completing Quest 9
Side Quest 9: Unique Piece of Collection
You accept this quest with Tika in the Shop of the Gods. You can find the item at the stomatch of the Glurose, in the spot where you find the Glurose in the ancient temple, instead of killing the animal king, just lose the battle and you will be transported to its stomach. Search the pillars and you'll find the item.
Side Quest 11: Kill Tukulu Nation
Kill the Animal King, Tukulu Nation. Found at the Secret Room 11 at Luhana Beach.
Side Quest 12: Kill Hippo-Quake
Kill the Animal King, Hippo-Quake. You'll find this in Jungle Kawa Kawa with Karine's party. It's in one of the lake areas easily spotted by a little area with smoke coming out of the lake.
Side Quest 13: Kill Glurose
Kill the Animal King, Glurose. You'll find this in Jungle Kawa Kawa while exploring with Karine's party. You can find by simply going through the jungle in a swamp area, it's part of the path that you need to go so you just stumble with it.
Side Quest 14: Kill Glurose
Kill the Animal King, Glurose. (DON'T DO THIS BEFORE FINDING THE SHOP OF THE GODS AND ACCEPTED TIKA'S QUEST)You'll find this one in Acient Temple, in a empty room with grass inside the Ancient Temple, just wait and it will come to you. Don't forget to lose the battle to be transported to a secret room.
Side Quest 15: Kill Metallicrab
Kill the Animal King, Metallicrab. You'll find him in Prehistoric Cave while exploring with Mom's party. In a cave shaped place.
Side Quest 16: Kill Dumerork
Kill the Animal King, Dumberork. Found in the Ancient Temple in a shining pilar while exploring with Blondie's party.
Side Quest 17: Kill Monkey-See-Monkey Doo
Kill the Animal King, Monkey-See-Monkey-Do. Found at Cactus Crest. Available in Hard Mode only.