To get the upperhand on the opponent you need to know what options that have against your strongest tools. So the next is to understand the weakness 5A has to low profiles, and learn our option to beat low profiles.
Mitsuru's option to Beat Low-profile goes to:
5B : Her 5B has lower-body invincibility so it can go over low profiles and fatal counter the opponent.
j.D : A lower risk option to beat low profiles, but also offers a lower reward.
Mitsuru's option to Low-Profile the opponent is :
Sweep : Mitsuru has a long range sweep that is a full low-profile and gives a big reward on hit.
Extremely important in Mitsuru's gameplay for her Strike/Throw mix and Fatal Counter punishes, however; the important part here is lower body invincibility.
When your opponent tries to counter play Mitsuru's oppresive 5A with low profiles, you can abuse the lower body invincibility of Mitsuru's 5B to counter poke the opponent for huge damage.
Though it's not the strongest poke, Mitsuru's sweep can be useful for a hard callout. It's not frequent that Mitsuru will need or want to low profile another character's pokes, but if necessary she has a tool for it.
Mitsuru has her three whip normals that are very useful in their own right at countering the opponent choices in neutral.
5D is particularly strong when the opponent is content with staying fullscreen, low is virtually none fullscreen if the opponent doesn't have a projectile and your reward is huge.
Her 2D is another move Mitsuru can use beside her j.A and 2B to keep people out of the air. It covers a more horizontal angle than her, giving all of her anti-air tools their own niche,
Lasty Mitsuru's j.D is really good, because it allows her to retreat and go for an attack at the same time at a pretty low risk. The reward along with all of her whip moves is really good so the low risk from retreating pairs well.