Arashi finds himself stricken with a peculiar condition known as Love Allergy, where manifestations like heart-shaped rashes, dizziness, and palpitations plague those who experience love. After a chance encounter with his childhood friend Haname triggers this allergic reaction, Arashi wakes up in a hospital bed covered in heart-shaped marks. To combat this Lovesickness, he is prescribed heart-shaped pills to suppress his emotions. Bereft of the ability to truly love, Arashi navigates a world where physical intimacy is possible, but genuine affection remains elusive. Amidst this struggle, the narrative delves into the intertwined fates of childhood friends grappling with a forbidden love due to their shared affliction. Unraveling alongside their tale is the nuanced backstory of their attending physician, Miyoshi-sensei, adding depth to this heart-patterned, pure love story.