Here is the full list of all 51 Hentai Sweet Battle achievements.
You have conquered this mysterious princess
You get Jenny's Crown
You have conquered this cute Kitty
You get Mia's Kitty Tail
You have conquered this beautiful Angel
You get Andrea's Wing
You have conquered this beautiful Female Elf
You get Rita's Holy Light
You have conquered this beautiful Female devil
You get Yuki's Devil Horn
You have conquered this beautiful Ninjia
You have clicked the mouse 10000 times on special stage
You get Nana's Eye Mask
You have conquered this beautiful kung fu master
You get Miko's Cheongsam
You have conquered this beautiful assassin
You have clicked the mouse 5000 times on special stage
You get Kelli's Scarf
You have conquered this beautiful warrior
You get Erin's Epic Sword
You have conquered this beautiful Priest
You have clicked the mouse 1000 times on special stage
You get Trish's Necklace
You have conquered this beautiful mage
You get Freda's Wand
You get Freda's Bag
You get Trish's Pauldrons
You get Erin's Shield
You get Kelli's Mask
You get Miko's Hair Clip
You get Nana's Ninja Sword
You get Yuki's Devil Blood
You get Rita's Elf Hair
You get Andrea's Feather
You get Mia's Kitty Bell
You get Jenny's Earring
You have conquered this beautiful knight
You get Celeste's Golden Cross
You get Celeste's Green Gem
You get Celeste's Red Gem
You get Jenny's Bow
You get Mia's Kitty Ear
You get Andrea's Golden Collar
You get Rita's Headwear
You get Yuki's Devil Hair
You get Nana's Headwear
You get Miko's Cloth Shoes
You get Erin's Leg Armor
You get Trish's Bracelet
You get Freda's Badge