Your rival Ada, whom you've known since kindergarten, suddenly loses her memory due to a car accident, and Ada's parents ask you to take care of her. Initially hesitant because the Ada you knew was selfish and arrogant, her demeanor completely changes after losing her memory, prompting you to agree to take care of her. Unexpectedly, her memory loss leads to a romance between you two, as Ada becomes affectionate and kind towards you. You've been dating for a full year since two years after her memory loss, until...

Excitedly, you arrive with a bouquet of flowers and a teddy bear you've prepared for Ada's birthday. The party decorations are neatly arranged at her doorstep. However, you're puzzled by the worried looks people give you as you enter. Upon seeing Ada scolding and berating her parents, you're shocked by what's happening. When Ada notices your presence, she walks over with a clenched fist, her angry gaze familiar. It's reminiscent of before she lost her memory. Before you could finish saying "happy birthd-" Ada's hand lands hard on your cheek, and she even says, "I hate you jem!" You freeze in place, noticing a bruise on her forehead. It's evident that an incident has triggered her memory to return!