Ky Kiske's Stun Dipper (236K) is a risky, but unusually quick, roundstart option that will beat any of May's attacking options at round start. May should block on first round start as a low-risk start that punishes this option.
May can punish Ky's Stun Dipper on block, depending on whether or not she is in shock state and Ky's spacing when he uses the move. If May is not in shock state, she can punish Ky with 5K>3K unless he is spaced well on normal block. If May is in shock state, the additional knockback makes Ky significantly safer. If May instant blocks one or both hits of this attack, she will be much closer - able to punish with 5K>3K consistently in shock state, or even with c.S in some cases.
6S is not going to be very good in this matchup. Ky's 2S punishes every offensive option May can use after it's blocked, at worst trading favorably with May's 2P. This leaves May with only backdash, block, or jump - none of which can punish 2S. Not only that, but if they wish to gamble, Stun Dipper will catch both backdash and jump, only losing to block. Its more favorable for May to close the distance with running or jumping and reserve 6S for fast punishes where other buttons wouldn't reach or be fast enough.
May can interrupt Ky's Foudre Arc on reaction with 6S or 5P. If Ky is close to May and May blocks Foudre Arc while standing and not in shock state, she is at a slight (1) frame advantage, which she can attempt to use to poke Ky out of his pressure extension with 2K. Beware that Ky gains frame advantage if Foudre Arc connects meaty, which always happens if May blocks it while crouching, and can also happen if Ky is well-spaced when he uses the move. Ky will also be at advantage if May is in shock state.
In general, Ky's pressure strings require very unsafe resets to extend without meter. If Ky is using meter to continue pressure, May should continue to hold defense until he ends his pressure string or goes for an unsafe reset without meter while watching for gaps and movement that can signal a throw attempt.
None of Ky's air attacks hit directly below or behind him. May can take advantage of this when Ky jumps at close range by running directly under him in neutral for an air throw or air counterattack from behind with j.K or j.D.
As a character with a meterless invulnerable reversal, Ky has an exceptionally easy time escaping from May's larger frametraps. May should be more careful about her pressure strings in this matchup as a result, and should use throw okizeme early to beat it as a wakeup. Most Ky players will attempt to burst out of a whiffed DP punish, so be prepared to bait the burst with c.S (CH) > block burst > c.S > ...