Here is the full list of all 36 Waifus Smash achievements.
Agreed to help the village chief
Find 8 Konjacs for Mina
Unlock the first campfire
Join the first enemy area
Clean 3 enemy groups
Rescue Rina
Complete Erika's quest lines
Complete Sakura quest
Defeat Fuji
Defeat Yuma
Pick up any flower
Defeat 30 enemies
Unlock all travel point
Open a chest
Exchange heart's part to a heart
Reaching maxium 20 heart
Choosing to don't drink the Dragon Blood
Placing bomb several times
Choosing to drink the Dragon Blood
Solve a music puzzle
Solve all music puzzles
Sell a precious item
Finish the main story
Kill 2 enemy continuously without beat skipping or missing
Kill 3 enemy continuously without beat skipping or missing
Kill 4 enemy continuously without beat skipping or missing
Kill 5 enemy continuously without beat skipping or missing
Death by a kiss of Succubus
Defeat the Golem of the Frostburn
Defeat Fuji without getting hit more than 5 times
Defeat the giant Orc
Defeat the corrupted Goddess of the forest
Defeat the fallen knight
Destroying the magic shield using the Blood Spiller
Unlocking the special magic wall using Fuji's charm
Find all red aura statue