"The human heart is but a vessel for pain." That's what someone once whispered―a voice laced with loneliness, whispering directly into the soul. It's an indescribable sadness, a love just beginning to bloom. It becomes an invisible pain that pierces the heart. And that's what makes up life: a cyclical series of highs and lows. Tachibana Sai was born without the ability to feel pain in his heart. He spends his days eliminating any seeds of malice that sneak up on his sister, the one person he treasures, without drawing attention to himself. Sick of the never-ending monotony he lives through, he chances upon a meeting with Benio Matsuri, a young girl whose aloof demeanor resembles that of a beautifully crafted doll. For the first time in his life, he encounters a heart-piercing sensation―that of falling in love. On the edge between day and night, in a twilight world where the dead and living mingle, stands an apartment building called Maison sans Nom, which is home to a group of boys and girls. A ruthless boy who knows no pain in his heart. A lonely girl without any friends. A friendly girl who struggles to make connections. A prickly, ambitious girl who is keen to be of help. A boy who loves his own cute self above anything else. A mess of a woman who tries to solve everything through brute force. And a boy with a tender heart who knows no pain in his body. This ill-assorted group of residents, hands stained with blood from battling the supernatural Maledicts, shall encounter the hearts they never knew and begin nurturing their souls. The human heart is but a vessel for pain. To protect this pain akin to love... To gently break the world apart, piece by piece... Even if it means abandoning humanity. That's why the heart is but a vessel for pain. For life blazes brilliantly, while the heart goes around in an endless cycle.