After catching a cold by giving his only umbrella to a girl sitting in the rain, Amane Fujimiya only expects her to eventually return it. However, Mahiru Shiina, the "Angel" of Amane's school and his neighbor, instead gives him a lot more than that. The only word Mahiru finds in her mouth to describe the chaos is "unsightly". But despite her unsympathetic description, Mahiru proceeds to help the hopeless Amane. Is there anything that the Angel can not do?