Why yes, he is. And he's my first OC of the Persona series!
His time takes place probably around the time of Persona 5 Strikers/Scramble. Attending a classy performing arts school rather than regular high school, Kaise stumbles upon a mysterious smartphone leading him into the Metaverse.
Kaise is naturally a bit rebellious, but tends to do more through words rather than actual action. As such, when he communicates with his Shadow, it manifests as a half mask and a puppet tied to his fingers. This allows him to summon his Persona and attack from longer distances compared to other users.
An interesting detail, is that Kaise's Metaverse outfit is NOT drastically different from his usual. The only true changes to his appearance is the mask, his hair falling freely rather than being in a topknot, the cape, and his toenails painted purple; he is always wearing a suit and has not worn shoes since the age of 10.