Tokyo stocks fell slightly Thursday, as investors locked in gains after four consecutive days of advances, while a stronger yen weighed on some exporters. The 225-issue Nikkei Stock Average ended down 141.62 points, or 0.42 percent, from Wednesday at 33,539.62. The broader Topix index finished 3.38 points, or 0.14 percent, lower at 2,362.02. On the top-tier Prime Market, decliners were led by marine transportation, mining and rubber products.