The present invention relates to the compound of formula (I) wherein R1A, R1B, R1C, and R1D are hydrogen atom, etc., R2A and R2B are hydrogen atom, etc., R3A, R3B, R3C, and R3D are hydrogen atom, etc., L is bond, etc., V is C1-6 alkylene, Q is optionally-substituted imidazole, or a pharmaceutically acceptable salt thereof, as a novel anti-tumor agent that targets CSCs which are thought to be closely involved in the persistent proliferation of malignant tumor, metastasis or recurrence of cancer, and resistance to anti-tumor agents.