Given that Ritsuka has virtually no offensive capability to speak of, that barrier is quite effective indeed. Which means she's back to dodging his attacks while looking for an opening. Those smaller pebbles might be little more than an annoyance, but one in exactly the wrong place at the wrong time could still make things difficult.

She'll just have to think of another approach, then, though in the mean time that sure is a lot of quick dashing around the arena.