My Hero Academia's Tsuyu Asui -- also known as the Rainy Season Hero: Froppy -- has a promising future ahead of her as one of the 40 first-year students in the elite Hero Program at U.A. High School. She's considered a well-rounded hero by her teachers, adept at rescue, stealth and combat while lacking any obvious weaknesses. There's no doubt she deserves her spot at U.A., unlike a certain classmate, and if she survives to the end of the series she'll easily rank in the top 50 of Japan's Hero Billboard Chart.
But even those accolades fail to acknowledge the incredible potential Tsuyu's Quirk gives her as a hero. Her Frog Quirk allows her to do "everything a frog can," much like Spider-Man from Marvel Comics has spider-themed powers. The exact capabilities and limitations of this Quirk aren't fully explored enough in the series but basic logic suggests we've only seen a fraction of its full potential. The main obstacle standing in the way of Tsuyu's Quirk being developed upon is that the series creator, Kohei Horikoshi, has sidelined most of his female characters when it comes to combat -- with the exception of Himiko Toga and Mirko. So far we haven't had many chances to see Izuku's female classmates shine on the battlefield, but Tsuyu's mere background feats prove she could be amazing if given the opportunity.
The series has established multiple times that Tsuyu has a versatile power-set. She's capable of camouflage, long-distance jumps, clinging to walls, producing mild toxins and paralytic agents, and perhaps most iconically, grabbing or flinging people with her extremely long tongue. Her powerful tongue in particular deserves closer scrutiny because it strongly suggests that Tsuyu has yet another ability thanks to her Quirk: superhuman strength.
The tongue is a powerful muscle by natural design, but even if an ordinary human had a tongue as long as Tsuyu's, they would be incapable of matching her strength feats with it. Tsuyu regularly lifts people several feet in the air with her tongue and flings them great distances; her tongue also has the strength to catch heavy moving objects without being ripped from her mouth. On top of that, these feats are achieved with only the tip of her tongue, which is where she'd be at her weakest, due to the tip being so far outside her center of mass. Consider for a moment how strong the main portion of her tongue must then be at close range -- it's nothing to sneeze at.
Many fans brush this off with the notion that even if her tongue is superhumanly strong, this strength is limited to her tongue and her tongue only. But one of the simplest laws of physics out there refutes this. Newton's third law of motion states that for every action, there is an equal and opposite reaction. In Tsuyu's case, this means that the rest of her body must have proportional strength in order to handle the impact and strain her tongue undergoes without flinching. Her tongue cannot lift people heavier than her and fling them long distances if Tsuyu is incapable of doing this as well.
Even if Newton's third law is dismissed with the idea that anime physics are often inconsistent, we know for a fact that Tsuyu's legs have superhuman strength thanks to all the incredible frog-like leaps she makes throughout My Hero Academia. The strength to leap high into the air should also lend formidable power to her kicks, which would vastly upgrade her battle utility if she incorporated this into her combat style. In this aspect, her powers strongly mirror the #5 ranked hero, Mirko, whose superhuman strength comes from her Rabbit Quirk. If Tsuyu's implied superhuman strength is combined with her sheer versatility, this would make her as strong, or potentially stronger, than Mirko once she's an experienced pro-hero herself.
Tsuyu Asui could easily rank in the top ten of all Japan's pro-heroes if her potential is fully utilized. The only question remaining is which Class 1-A students will get that time to shine.