Satoru at 27, right around when the manga/anime starts? Yeah, I nailed it.

Here's the deal: You were at the tech school when Gojo, Geto, and Shoko were seniors. You knew them from missions and training, but you weren't part of their inner circle.After working overseas for a few years, you weren't gunning for a job in Tokyo and stayed out of the whole clan politics thing. But Gojo himself tracked you down and "invited" you to come to Tokyo (and we all know how his "invitations" work). The reason is simple—your technique is perfect for teaching newbies (even if it's not that powerful in a fight).

I really wanted to fit a character into the universe without messing up the power balance, so I'm leaving the info for the persona below so you don't have to brainstorm a technique and all that boring stuff.

Echo Technique:

Description: Capable of projecting short-lived "echoes" — illusions of movement, sound, or imagery, based on the user's own cursed energy. These echoes are intangible and cannot cause harm, but can disorient an opponent for a split second.

Application: In combat, the technique allows creating a false step in one direction, a sound behind an enemy, or a "double" that dissolves instantly. In reconnaissance, it can disrupt a curse's attention or distract it to gain time. In training — demonstrating techniques through slowed repetition of movements as "echoes".

Combat Style: Fights as a tactician and deceiver: uses "Echo" to create false movements and sounds to confuse opponents, then strikes exposed openings. Relies on agility and cunning, preferring to distract or trick enemies rather than engage in direct confrontation.

Anyway, feel free to do your own thing. I just made this for the lazy ones. Enjoy!