Like a wilted flower, university student Mizushima's mother passed away when he was 12 years old. Since then, he has been perpetually depressed and isolated. To distance himself from his loss, Mizushima fixates obsessively on an endeavor to invent an "eternal flower," one that will never wither. Sacrificing his health, Mizushima continues in a downward spiral to advance the project, but his world soon begins to lighten after he meets Hanamori, a bright and lively girl who works at the local flower shop.

Hanamori's infectious cheerfulness steadily ameliorates Mizushima's nihilistic worldviews and poker-faced demeanor. As the two spend more time together, their relationship gradually blossoms—and Mizushima may finally discover what gives meaning to life.