Tokyo stocks ended slightly lower by midday Monday as investors locked in gains after Friday\'s sharp rally amid a dearth of major trading cues. The 225-issue Nikkei Stock Average lost 12.91 points, or 0.09 percent, from Friday at 13,647.64. The broader Topix index of all First Section issues on the Tokyo Stock Exchange was down 0.61 point, or 0.05 percent, at 1, 141.02. Decliners were led by airlines, sea transport and tire issues, while gainers included real estate, miscellaneous products and services shares.