Tokyo Electric Power Co. on Thursday reported a group net profit of ¥616.20 billion for the April-September period, swinging into the black on a half-year basis for the first time since the nuclear disaster at its Fukushima No. 1 complex in 2011.

Cost-cutting efforts and household electricity rate hikes also helped the utility to log a pretax profit of ¥141.66 billion, but Tepco President Naomi Hirose said that becoming profitable in the full business year is still "tough" because expenses tend to rise toward the end of the year.

"We must avoid incurring a (unconsolidated) pretax loss for the third consecutive year," Hirose told a press conference, referring to the promise Tepco made in return for receiving a capital injection of ¥1 trillion from a state-backed fund in July last year.