In March 2015, Deimantė won the Mediterranean Flower round-robin tournament in Rijeka. In the following month, she competed in the Women's World Chess Championship 2015, where she lost in dramatic style in the 1st round. Her opponent was Monika Soćko. After drawing the first 2 games, it went to a tie-break. Deimante won the first rapid chess game. In the 2nd game of the tie-break, she reached a position where she could checkmate the king in 1 move. Instead of playing the winning move though, she played a move that lost her her queen. As a result, she lost that game. She didn't recover from that, and lost the next 2 games as well.