TOKYO, March 25 (Reuters) - Japan's Nikkei share average rose for a ninth straight session on Friday, its longest winning streak since September 2019, as investors bought back cheap stocks even as a recent rally partially prompted traders to lock in profits.

The Nikkei share average reversed course to inch 0.14% higher to 28,149.84, with the index gaining 4.93% this week.

The broader Topix ended flat at 1,981.47, but posted a weekly gain of 3.78%.

"Market uncertainties have been removed and that has prompted investors to buy stocks," said Masahiro Ichikawa, chief market strategist at Sumitomo Mitsui DS Asset Management.

"Investors have digested the impact of the ongoing Russian-Ukraine war, while the U.S. rate hikes have already been factored in."

Chip-making equipment manufacturer Tokyo Electron boosted the Nikkei the most with a 0.63% climb.

Shionogi jumped 4.49% after the drugmaker signed a basic agreement with the Japanese government to supply an oral COVID-19 treatment it is now developing.

Fanuc rose 0.89% after the autonomous firefighting robot maker announced a share buyback programme.

Technology investor SoftBank Group and phone company KDDI weighed on the Nikkei the most, falling 0.25% and 1.85%, respectively.

Banking giant Sumitomo Mitsui Financial Group fell 1.83% after executives at its brokerage unit SMBC Nikko Securities were arrested and indicted for alleged market manipulation.

There were 135 advancers on the Nikkei index against 84 decliners.

The volume of shares traded on the Tokyo Stock Exchange's main board was 1.19 billion, compared with the average of 1.38 billion in the past 30 days.

(Reporting by Junko Fujita; Editing by Subhranshu Sahu and Sherry Jacob-Phillips)