After Japan's defeat in WWII, "Pandora no hako" follows a young man named Risuke (Shota Sometani) who has contracted tuberculosis. He travels to the countryside to a unique nursing facility to receive treatment for his disease. At the sanatorium all the patients and nurses go by nicknames and Risuke decides to reinvent himself as Hibari. During his stay, Hibari develops realationships with other patients and nurses. After Hibari's friend Tsuikushi (Yosuke Kubozuka) gets discharged from the nursing facility, Hibari writes to him about his relationships with Dakesang (Mieko Kawakami) the chief nurse and Mabo (Riisa Naka) another nurse that is bright and seems to like him.

太平洋戦争中、体の弱さから自分を余計な者だと思い悩んでいた少年・利助。結核を患う彼は、終戦を機に山奥の結核療養所、健康道場へ入所する。少々風変わりな健康道場での日々を過ごす中、ひばりと名付けられた利助は、新しくやって来た看護婦長・竹さんのことが気になり始めるが…。