There are a plethora of tropes within both current and past anime series. These range from iconic trends, such as characters shouting attack names, to the more negative recurrence of weak female love interests. Regardless of how each of these is considered, anime tropes remain highly distinctive and an important part of understanding the history and ideas contained within a number of shows.
The Henshin Hero is a trope that has become ingrained within many action-packed series, from Sailor Moon to Bleach. Henshin was a term that was popularized through the Kamen Rider series, where it would often be called out to indicate when a Kamen Rider was ready to transform. The meaning of this phrase simply translates to "transformation," specifically when an alteration to the body occurs.
The Henshin Hero is a sub-trope of the superhero genre, in which a character has super-powered traits but can only use them at a particular time or place. Consequently, this type of character has two distinct forms: a normalized and a powered state.
In order to access their super abilities, Henshin Heroes often have a special item that can come in a variety of forms, including utility belts, wristbands, jewelry and various other trinkets. These items either act as the source or focusing mechanism of their shapeshifting powers. Ichigo’s use of a substitute soul reaper badge to expel his soul from his physical body is a good example of how Henshin Heroes use objects to activate their powers, and one that many anime fans are likely familiar with.
A Henshin Hero's ability to shift between powered and non-powered states is simultaneously one of their greatest strengths and weaknesses. Typically, the benefit of being a Henshin Hero compared to a regular superhero is that they are able to integrate within society more easily. Usagi Tsukino (Sailor Moon), Yohko Mano (Devil Hunter Yohko) and even All Might (My Hero Academia) have the capacity to live normal lives after their powers are deactivated.
However, this benefit typically causes as many problems as it solves. Henshin Heroes are often caught off guard when their foes discover their secret identity, are unable to transform at a pivotal moment or lose their special item. In Yu-Gi-Oh!’s 51st episode, “The Mystery Duelist, Part 2,” Yugi has his Millenium Puzzle stolen by Bandit Keith, who is under the spell of Bakura’s Millenium Ring. This leaves the show's protagonist unable to transform and gain access to the hidden powers of the Pharaoh so that he can more easily defeat his opponent.
The significance of this trope in anime cannot be overstated. The Henshin Hero arguably offers audiences a more relatable experience with a character than is usually possible with the more traditional superhero. Instead of a character being endowed with magnificent powers from birth, they are given to them through the use of an item, which in most cases any normal person could use. This enables the viewer to more easily place themselves within their favorite protagonist's shoes and imagine what they might do if they had the opportunity to become a Soul Reaper, magical schoolgirl or even a Digimon.