After the passing of his parents, Koutarou finds himself managing their coffee shop alone. His only companion is a cat and, despite concerns from those around him about his loneliness, Koutarou struggles to forge deep connections with others. One day, a self-proclaimed angel appears before him—Rudy.

"I've been waiting. I want to hear you sing," Rudy says.

Koutarou's heart skips a beat; he had abandoned music a long time ago. Rudy decides to move in with Koutarou—not that Koutarou agreed to anything—and, from there, their life as housemates begins...

(Source: Futabasha, translated)