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