Mahiru Shiina is honored with her nickname "Angel" because she is considered a divine beauty admired by everyone, excelling both academically and athletically. She resides in an entirely different world than Amane Fujimiya, who lives next door. Despite their proximity, they have never spoken until Fujimiya notices Shiina sitting gloomily on a swing during a heavy rainstorm and offers her his umbrella. When Fujimiya catches a cold the following day, Shiina promises to return the favor by taking care of him in exchange for the umbrella. Initially, she only wants to repay his kindness but begins helping him cook and clean secretly out of concern for Fujimiya's cleanliness and nutrition. Over time, their relationship grows closer as they spend more time together, revealing deeper emotions that defy expectations.
Amane discovers a drenched Mahiru and lends her his umbrella, only to fall il...