Shadow Ring

Shadow Ring (シャドーリング, Shadōringu) is the A-Class Rank 32 professional hero from the Hero Association and a ninja from an unknown village.

Appearance
Shadow Ring's attire consists of a black ninja garb that completely covers her face and body.

Personality
Shadow Ring appears to have a very reserved personality. She was visibly stunned by Flashy Flash's speed and admired his ninjutsu skills.

History
Shadow Ring trained at a ninja village different from the one that Flashy Flash trained in.

Monster Association Arc
Shadow Ring is one of the heroes recruited to the support group for the main Monster Association strike team. When the monsters ambush the heroes, she attacks along with her fellow heroes. She mows down several monsters with her shurikens, when a monster comes up from behind her and slices her head straight down the middle, however it was revealed to be a trap, while the real Shadow Ring slices the monster's head clean off. Shadow Ring sighs in relief, when Flashy Flash compliments her movements, asking her in what village she trained. Shadow Ring replies that it wasn't the same as his, and runs back into battle. As the second wave of monsters arrives and Rhino Wrestler attacks the heroes, Shadow Ring sprints up to him and strikes him with her sword, but Rhino Wrestler shrugs it off, giving her a measly 10 points out of 100. Then, while Iaian holds Rhino Wrestler in place, Shadow Ring strikes the monster along with many other heroes, but she is blown away along with the other heroes.

After Rhino Wrestler is defeated and Atomic Samurai eliminates a large horde of monsters, Flashy Flash decides to kill a large group of them. Shadow Ring witnesses this and marvels at his amazing speed, noting she couldn't see him at all.

Abilities and Powers
Being an A-Class hero, Shadow Ring is a rather powerful individual. She is complimented by Flashy Flash for her combat skills. However, in the face of Demon-level monsters, she is shown to be outmatched, as seen with her battle against Rhino Wrestler.

Physical Abilities
Enhanced Strength: Being an A-class hero, Shadow Ring has rather impressive physical strength and is able to dispatch several monsters with ease.

Enhanced Speed: As a ninja, Shadow Ring is naturally fast, as she was able to react to a monster striking from behind her, replacing her head with a wooden plank and slicing its head off in an instant.

Enhanced Reflexes: Shadow Ring has very good reflexes, being able to react to a sneak attack from behind in a very quick amount of time.

Fighting Style

 * Ninjutsu: Trained in a ninja village, Shadow Ring has demonstrated that she is proficient at ninjutsu.
 * Body Replacement Technique: Shadow Ring replaces her body with a block of wood to misdirect his opponents.

Equipment
Katana: Shadow Ring uses a katana with a black square guard and a black hilt.

Shuriken: Shadow Ring uses numerous shuriken to attack monsters from a distance.

Trivia

 * Shadow Ring is the first female ninja shown and the only ninja without a redundant name e.g Flashy Flash, Speed-o'-Sound Sonic, Hellfire Flame and Gale Wind.
 * Yusuke Murata considered giving Shadow Ring an unexpected look underneath her ninja garb.
 * It's a Japanese trope based on the actual legends built up around historical Ninjas (probably also by said Ninjas, for whom misinformation was a great tactic). "Kawarimi" was a supposed technique possessed by the ancient Ninja that used misdirection and split-second timing to swap places with something that could easily be mistaken for the Ninja.

There may be some historical grounds for this, but not to the extent we see in Naruto. Instead, this could easily be a trick used by historical ninja to trick and mislead enemies, and build up the mythos they had constructed for themselves. As an example, a Ninja may have previously prepared a wooden dummy that was about his size and dressed it in the same clothing as he was wearing. This dummy could be hidden somewhere convenient for later use. Then, when fleeing pursuers, you head back to where you hid the dummy and in a moment where your pursuers lose track of you (either with natural obstacles or a smoke/flash explosive set off), you set the dummy in your place and go the other direction. You could even set it up to go over a cliff. While your pursuers are distracted by the dummy, you slip away. Thus was built up the legend that Ninjas could 'trade places' with things, and since wooden (or straw) dummies were convenient for those purposes, they likely got used the most.

Over time, this morphed in Japanese culture along with a lot of the other myths of the Ninja. For example, the myth of Ninja dressing in all black growing out of Kabuki Theater (Stage hands dressed in all black, and so theater goers were used to completely ignoring them...so when one of them jumped out and drew a sword, it was as if they had appeared from nowhere...allowing the theater to have 'super-stealthy Ninjas'). Over this time, the idea of the Kawarimi morphed and changed until it landed on them simply swapping places with a log. Even the particular appearance of the log is somewhat standardized in this trope: a short round chunk of wood of about the same thickness, either completely smooth or with a single 'stump' branch coming off the side.

It turns up in quite a number of places, from other anime and manga to a bunch of video games. In short, in Japanese culture, the "kawarimi log" is simply the standard thing for a Ninja to swap places with, without regard for where it came from. It's the same idea as how, in American culture, if something is blindly tossed out a window, there will be a cat down there that yowls and knocks over a bunch of stuff over...or how no one questions that saying "Well, at least it can't get any worse" will instantly make things worse...or how someone can put on a pair of glasses, and that is considered a solid disguise.