After she was defeated by Hitoriga in their first confrontation, Suzuka trained to become a better fighter in order to avenge the deaths of her family and master. When she finally encountered the assassin within the Galactic Leyline, she allowed herself to be harmed by one of Hitoriga's attacks to get a sense of his full strength and the pain he afflicted on those he harmed.
When Hitoriga attacked her using the same move again, she deflected the attack with a swing of her Bokken, which allowed her to rush forward without recourse from the Kei Pirate. She used a single slash move that cut through and killed him.
Crimson is arguably the strongest move in Suzuka's repertoire. It can be used either while running or standing still.