Typically, an anime character's power is supposed to be their greatest asset. It defines their strengths, limitations, and in many instances, personalities. Powers are especially popular in shonen, where every person is given one ability that they hone over time with practice.
However, there is a bizarrely high number of characters who refuse to harness their abilities for one reason or another. As a result, they are noticeably selective when it comes to using their powers. Some of them outright refuse to tap into their potential. It's easier to determine if their restraint is justified by examining their unique situations and what they're powers entail.
10 Nighteye Doesn't Want To See Far Into The Future (My Hero Academia)
Nighteye technically uses a small amount of his Quirk in order to see the next five seconds. This allows him to remain a competitive professional hero regardless of his unimpressive physical skills. However, he refuses to harness the full power of his Quirk.
After seeing All Might's potential death, he chooses to remain ignorant of the distant future on a matter of principle and the substantial emotional distress it will cause him for doing so. In the end, Nighteye's Quirk would be much more formidable with a different user.
9 Escanor's Power Risks Killing Everyone Around Him (Seven Deadly Sins)
Escanor's "Sunshine" grace allows him to become proportionately more powerful based on the time of day. For reference, he grows so hot that his comrades boil in their own armor by roughly eleven in the morning.
As a result, Escanor seldom uses his power unless absolutely necessary to protect his comrades. He is especially sensitive about the nature of his abilities since they made him an outcast as a child. Escanor does not wish to relive the past or put friends in harm's way.
8 Killua Doesn't Want To Exploit Alluka's Gifts (Hunter X Hunter)
Alluka was Killua's sibling and the most prized asset of the Zoldyck family. Her ability to grant wishes was extremely overpowered since it could effectively bring people back from the verge of death. Unwilling to let his father exploit her any longer, Killua rescued Alluka from the mansion.
There are two reasons he does not call upon her tremendous power. Not only does he want her to live like a normal kid, he understands that with every wish, comes an even greater demand from her dark half, Nanika.
7 Frieda Reiss Is Bound By Karl Fritz's Will (Attack On Titan)
As an heir of the royal family, Frieda Reiss inherited the Founding Titan upon reaching adulthood. In theory, this granted her the power to control the entire Eldian race and even wipe out the world with the Rumbling.
However, Frieda never really had the will to make those decisions for herself. Every user of the Founder's power was bound by the will of the late Karl Fritz. As a result, she effectively spent the rest of her life as a slave to her ancestors without ever having a chance to unleash her great potential.
6 Jugo Does Not Like Giving Into His Violent Impulses (Naruto)
Jugo was one of Orochimaru's former experiments and a member of the Sound Village. Sensing his usefulness, Sasuke recruited him amidst his mission to avenge himself. Typically, Jugo remained a passive and gentle man that abhorred violence. However, he transformed into a bloodthirsty barbarian whenever he accesses his ability.
Though strong enough to withstand punches from the Fourth Raikage, Jugo was still deeply uncomfortable with tapping into his power and only did so sparingly. Unlike other shinobi, he failed to control his curse nearly as well.
5 If Masazo Used His Power, He Would Die Instantly (JoJo's Bizarre Adventure)
Masazo had a very good reason for abstaining from using his Stand. Not only did it threaten innocent people, it would also kill him instantly the second it took effect. Cheap Trick transferred itself from one user to the next by looking at their backs.
The only safe way to get rid of it was through Reimi's haunted alley. Otherwise, the remaining alternative to "defeat" Cheap Trick is if the user killed themselves before accidentally transferring it. As a result, it is the worst Stand in the entirety of JoJo's.
4 Seras Victoria Did Not Want To Indulge Being A Vampire (Hellsing)
Seras Victoria was a young woman who Alucard transformed into a vampire. Though it significantly enhanced her strength and speed, her refusal to drink blood was problematic. It meant that she could not fully embrace the scope of her abilities and constantly made her feel fatigued.
Though she could hold her own against lesser opponents, the Millennium Organization pushed her into drinking the blood of a fallen comrade in order to defeat them. Under ordinary circumstances, she would have refused in order to retain her humanity.
3 Chopper's Monster Point Put His Friends At Risk (One Piece)
Chopper first debuted his "Monster Point" technique in the Enies Lobby arc and defeated Kumadori. Powerful enough to crush castles and ravage CP9's "Iron Body," it was easily the doctor's most formidable move.
However, his inability to control it put Nami in danger. Even after refining the Monster Point during the time skip, it still put an enormous toll on Chopper's body. As a result, he almost never uses it and prefers Kung Fu Point instead.
2 Miroku's Wind Tunnel May Kill Him If Overused (Inuyasha)
Miroku's "Wind Tunnel" was technically a curse inflicted on him by Naraku. It devoured everything in his path with a black hole that widened over time. Fortunately, Miroku managed to get it under control using prayer beads. However, he still refrains from weaponizing it for a number of reasons.
Not only will the wind tunnel slowly destroy his body when casting it, it instantly kills allies sucked into its powerful grip. To make matters worse, vacuuming poisonous things like Naraku's bees will damage the user exponentially and exacerbate the already high toll it takes on him.
1 Todoroki Did Not Use His Full Quirk On A Matter Of Principle (My Hero Academia)
Todoroki's full Quirk allowed him to summon both fire and ice in massive quantities. However, he did not use it on a matter of principle based on the abuse that Endeavor put him through. Having felt unloved and mistreated as a child, he saw his flames as an extension of his father.
Fortunately, Deku convinced him to embrace his Quirk as his own at the Sports Festival. While it took time for the message to fully stick, Todoroki eventually reached his unmitigated potential several seasons later.