Here is the full list of all 28 Strawberry Vinegar achievements. It takes around 0-1 hour to unlock all of the achievements on Windows.
Became Licia's (long-suffering) girlfriend.
Ordered a hamburger steak.
Ate candyfloss.
Became Licia's best friend.
Savored a strawberry sundae.
Ordered omelette rice.
Ate pickled plums.
Baked Licia a cake.
Made Licia some chicken cutlet sandwiches.
Said a sad farewell.
Made Licia strawberry risotto.
Made Licia rice porridge.
Made Licia pancakes.
Ate chichi dango.
Baked apple rose tarts.
Forgot everything.
Bought Licia a crêpe.
Bought Licia an onigiri.
Embarassed a fearsome demon.
Watched a fearsome(?) demon eat a corncob.
Ate shaved ice.
Ate takoyaki.
Gave Licia a chestnut pudding.
Ate tempura shrimp - plus sides!
Ate natto (begrudingly).
Encountered a fearsome demon.
Baked cookies.
Ate miso soup.