5. Myoga (Inuyasha)

Myoga’s name apparently means “divine protection,” which is ironic because he largely only protects himself. To be fair he was a member of the flea Yokai, which was the smallest demons bugs. Myoga was the servant of Inuyusha’s father Toga. As such Myoga tendency to flee prior to battle is seen as a warning of danger. If he’s present then that’s the most safe area to be. Myoga is willing to save others by drinking blood. Of course he has a bad habit of drinking blood without permission. His lack of fighting power may make his cowardly behavior is understandable but doesn’t change the fact that he’s a coward.

Source: Inuyasha wiki

4. Marechiyo Omaeda (Bleach)

Most lieutenant in Bleach are weak and useless, but most aren’t cowards. Marechiyo Omaeda is a victim of his privilege. He comes from a rich family, is generally, vain, greedy, and lazy. Despite this, he’s willing to be used as a decoy in a fight. During the Fake Karakura Town arc he quickly beaten by Nirgge Parduoc. During their encounter Omaeda runs from Nirgge. His captain Sui-Feng routinely berates him for being weak and useless. Once Sui-Feng faces Baraggan Louisenbairn, Omaeda distracts the Espada by running from him.

Source: Bleach Wiki

“Look. It’s a strategy. The other guys are wearin’ ’em down in the first round and I’m savin’ my energy for round two.“

— Yajirobe 

3. Yajorbi (Dragon Ball Z)

Yajorbi is a ronin. Despite the toughness samurai invoke, Yajorbi undermines that toughness. He’s a loner. Spending most of his time on Korin Tower. Yajirobe avoids fighting despite being skilled with his katana. He avoids major fights when possible, especially with King Piccolo and Vegeta. He would consider himself as “intelligently careful.” Yajorbi will aid other, specifically by giving them senzu beans. One of Yajorbi’s most well known moments of heroism is saving Goku from Vegeta during the Vegeta Saga. He would later interfere again slicing Vegeta down his back. After claiming credit for defeating Vegeta, Yajorbi is savagely beaten by Vegeta.

Source: Dragon Ball Z

2. Usopp (One Piece)

Usopp was introduced as a coward who tells tall tales exaggerating his life and abilities. His cowardice was the result of “his fear and insecurity.” He can overcome this when his friends are in danger. He often uses lies to avoid fighting or otherwise putting himself in danger. He claims he has a disease called “Can’t-get-on-this-island disease.” If he can’t avoid conflict he will use tall tales specifically claiming he was a Captain to try to scare his opponents.

Usopp’s insecurity flairs up when he’s reminded how inferior (in power) he is compared to Luffy, Sanji, and Zoro. His lack of belief in himself is a significant reason for his fear. Usopp is a talented sniper and his father, Yasopp, is one of Shanks crewmembers and assumed to be powerful. Usopp has made progress being more willing to risk himself without deception, he still avoids conflict and snipes from a distance when necessary.

Source: One Piece Wiki

1. Zenitsu Agatsuma (Demon Slayer)

I’m anime only so I don’t know if or how he’s changed.

When introduced in the Demon Slayer, Zenitsu is unlikeable. His constant wining and cowardly demeanor is irritating. He has low self-esteem, assuming his death is emanate. Like most of these anime “cowards” Zenitsu doesn’t like who he is. He inspires to live up to the standards others set. However, he lives in a constant state of fear that paralyzes him. What sets him apart from the other cowards is his actual power. During Tsuzumi Mansion Arc, Zenitsu shows his cowardly behavior, strength, and courage.

Zenitsu is chased by the Tongue Demon. He falls asleep (more like passes out). This is the first time we see the Thunder Breathing technique and it’s epic. However, after killing the demon, Zenitsu immediately wake up and assumes that Shoichi did it. Outside we get a glimpse of his courage as he takes a beaten from Inosuke while protecting Nezuko. His cowardly personality becomes less grating after awhile and funnier. Many cowardly characters, particularly the heroes have sophisticated reasons for their fears. They hope to develop more courage so they can save others. It’s actually arrogant villains like Freiza or Muzan that mask their cowardice with violence and cruelty, and never seek to overcome it.

Source: Demon Slayer Wiki