A randomized phase III trial commenced in Japan in February 2018. Definitive chemoradiotherapy (CRT) with cisplatin plus 5-fluorouracil is the current standard treatment for locally advanced unresectable esophageal carcinoma. The purpose of this study is to confirm the superiority of induction chemotherapy with docetaxel plus cisplatin and 5-fluorouracil (DCF) followed by conversion surgery or definitive CRT over definitive CRT alone for overall survival (OS) in patients with locally advanced unresectable squamous-cell carcinoma of thoracic esophagus. A total of 230 patients will be accrued from 47 Japanese institutions over 4.5 years. The primary endpoint is OS, and the secondary endpoints are progression-free survival, complete response rate of CRT, response rate of DCF, adverse events of DCF and CRT, late adverse events and surgical complications. This trial has been registered at the Japan Registry of Clinical Trials as jRCTs031180181.