Seven & i Holdings Co. is considering selling its department store unit Sogo & Seibu Co. due to slumping business amid the coronavirus pandemic and increased competition with online shopping operators, sources close to the matter said Monday. The plan emerged as ValueAct Capital, a U.S. investment company with a 4.4 percent stake in Seven & i, is stepping up pressure on the major Japanese retailer to sell the department store business. Seven & i, the Tokyo-based parent company of Seven-Eleven Japan Co., is expected to hold talks with the San Francisco-based ValueAct and other shareholders abou…