TOKYO, March 28 (Reuters) - Japan's Nikkei index slipped on Monday, snapping a nine-day winning streak, as investors locked in profits ahead of the fiscal year-end this week.

The Nikkei share average ended 0.73% lower at 27,943.20, following an almost 12% surge over nine days that included the benchmark touching a five-week high of 28,338.81. The broader Topix slid 0.41% to 1,973.37

"It's not surprising that after a nine-day winning streak, there would be a strengthening sense of caution about taking stocks higher," said a trader at a domestic securities firm.

"It's natural that profit-taking would be the focus of trade now."

The Nikkei finished the day of its lows though, buoyed by the Bank of Japan's (BOJ) twin offers to buy an unlimited amount of 10-year government bonds, displaying its commitment to its uber-dovish yield curve control policy as the benchmark yield reached the implicit policy ceiling.

The yen weakened past 123 per dollar following the BOJ's action, supporting shares of exporters. Toyota Motor rose 0.59%, while Nissan rallied 1.81%.

There were 123 decliners in the Nikkei index against 95 advancers, while seven were flat.

Energy shares were the best-performing sector, rallying 1.61%, with crude oil prices still at very elevated levels despite a sharp pullback on Monday.

Basic materials were the biggest drag with a 1.75% slump.

Japan's chip giants also retreated, tracking a drop in their U.S. peers in the previous session. Tokyo Electron dropped 1.31% and Advantest dipped 1.04%.

The biggest loser by index points was Uniqlo store operator Fast Retailing, sliding 1.79%.

Pacific Metals was the Nikkei's biggest percentage decline, dropping 6.64%, followed by Toho Zinc's 5.41% slide.

Startup investor SoftBank Group, which is heavily invested in China, erased an earlier decline to finish unchanged amid a rally in Hong Kong-listed tech shares, despite a coronavirus lockdown in Shanghai. (Reporting by Tokyo markets team; Editing by Sherry Jacob-Phillips and Uttaresh.V)