Japanese trust banks will reportedly sue Toshiba over its 2015 accounting scandal, a new headache for the conglomerate as it scrambles to offset a separate imminent multi-billion dollar writedown.

The news reported by Reuters follows an announcement by Toshiba on Friday that it will sell a minority stake in its memory chip business to raise funds and that its overseas nuclear division was now under review.

Chairman Shigenori Shiga is ready to step down to take responsibility for the upcoming charge - estimated at around $6 billion, local media have also reported.

Mitsubishi UFJ Trust and Banking Corp said on Monday it is preparing to seek 1 billion yen ($8.7 million) in damages on behalf of its client pension funds after Toshiba's shares slid in the wake of the accounting scandal two years ago. The bank is a unit of Mitsubishi UFJ Financial Group.

Two other trust banks, Sumitomo Mitsui Trust Bank Ltd and Mizuho Trust & Banking Co are also preparing similar suits, Reuter's unnamed sourced added.

In October, Toshiba said 45 overseas institutional investors filed a suit seeking 16.7 billion yen in damages since it first admitted to reporting inflated profits going back to 2008. That is in addition to suits from 15 groups and individuals in Japan that total 15.3 billion yen.