Eisai Co., Ltd. engages in the research and development, manufacture, sale, and import and export of pharmaceuticals. The company offers Dayvigo, an orexin receptor antagonist for the treatment of insomnia; LEQEMBI, a humanized immunoglobulin gamma 1 (IgG1) monoclonal antibody for Alzheimer's disease; Lenvima, an orally available multiple receptor tyrosine kinase inhibitor for the treatment of thyroid cancer and hepatocellular carcinoma, thymic carcinoma, renal cell carcinoma, and endometrial carcinoma; Fycompa, an anti-epileptic agent for primary generalized tonic-clonic seizures; and Halaven, a microtubule dynamics inhibitor for breast cancer and liposarcoma. It operates in Japan, China, the Americas, Europe, the Middle East, Africa, and East Asia Global South. The company was formerly known as Nihon Eisai Co., Ltd. and changed its name to Eisai Co., Ltd. in 1955. Eisai Co., Ltd. was incorporated in 1941 and is headquartered in Tokyo, Japan.