TOKYO — Toshiba, the struggling Japanese technology conglomerate, has been locked for months in a complex dance over the sale of its $18 billion microchip business. In a series of dizzying turns, Western Digital, the American data-storage company, has acted as a supportive business partner, a would-be acquirer and a bitter legal adversary.

Toshiba said on Thursday that it had resumed talks with other bidders. It previously rejected deals with Western Digital and Foxconn, the Taiwanese contract electronics manufacturer.

Just weeks ago, Toshiba had announced plans to sell the chip unit to a group of investors. It needs to get rid of the business to keep the company’s finances from unraveling, but the deal angered Western Digital and set off a public battle.

Toshiba’s announcement on Thursday came on the eve of an arbitration hearing in the dispute with Western Digital, with a hefty prize at stake: Whichever eventually wins control of the microchip unit will become a major player in NAND flash memory, the technology used to store data in millions of cellphones and digital devices.