StoryChapter Covers
Chapter 207 Cover
Sethan (セト神, Seto-shin) is the Stand of Alessi featured in the third part of the JoJo's Bizarre Adventure series, Stardust Crusaders. It manifests itself within Alessi's shadow and takes on the appearance of a humanoid with a bird-like head. Anyone who touches it will be de-aged.
Sethan is bound to Alessi's shadow, taking its form but with a distinguished shape, the most prominent feature being its round head, a pointed crest, and large eyes. If the shadow is sideways, Sethan's cruel, jagged beak is revealed.[1] Its design is based on the opening of the Tetsujin 28-go anime, as well as the Nazca geoglyphs.[2]
In the colored manga, Sethan's shadow is purple. In the anime, it is portrayed as black.
Sethan represents the Egyptian God of chaos and storms, Set.
Sethan has no personality of its own and only does what its user wills it to.
Sethan is a weak Stand with almost no offensive options, relying on its esoteric power to make its opponent weaker than Alessi. However, this alone makes it a terrifying opponent to face.
Because Sethan takes on the form of Alessi's shadow, it imitates and replicates everything he does and has.[1]
Because of this, any weapon Alessi holds is also held by Sethan, allowing it to attack the opponent with the shadow of the weapon.[3] Moreover, the shadow can move independently from its possessor and even partially stick out of a surface to attack.[1][3]
Anyone standing in Alessi's shadow will age backward at a rapid speed.[1] Polnareff, who touched it for a split second, ended up as an approximately 7 or 8-year-old child,[1] while Malèna stood in it for ten seconds and was transformed into a helpless fetus[4] that, without the connection to a womb, would have died within minutes. If a Stand user is de-aged to before they acquired their Stand like Jotaro, they will temporarily lose it.[5]
The mind of the target also ages backward, making them forget things they only knew as an adult (like names of friends or how to manifest a Stand), as well as de-aging their Stand itself.[3]
However, this Stand is not without its downsides; if the victim happens to be reduced to an age at which they were particularly physically adept, as was the case with Jotaro, then Sethan's usefulness can be significantly decreased at best and outright turned to a detriment at worst. Also, if the user is knocked out, all the victims it affected will revert back to their original state.[5]
Chapter 207 Cover
Summoned to assassinate Polnareff
Sethan's stats
Sethan's silhouette from JoJo Sono Chi no Kioku ~end of THE WORLD~
Sethan in JoJo's Pitter-Patter Pop!
Chara Heroes; Part 3 Vol.3
Weekly Shonen Jump #13, 1997