When the move is used, Joker will shoot a grappling hook upwards at an angle while being boosted up slightly (although the boost only works once in the air). It acts as a tether recovery, similar to the Ice Climbers' Belay and Ivysaur's Vine Whip, and can pull opponents closer to Joker if it hits them while Joker is grounded. If used in the air, the move instead has a weak hitbox that can be used to push the opponent into the blast zone if they're already close. This move is classified as a projectile and thus can be reflected.
Upon the throw's success, Joker gains enough frame advantage to always hit a forward aerial up until around 110%, giving the move a lot of utility. Grappling Hook's grab hitbox will not work if the opponent is already in hitstun, limiting its use to starting combos, not continuing them. It also does not work on shielding opponents, akin to Isabelle's Fishing Rod. It also has very few ways to confirm into it, with the last hit of up aerial while Joker is close to the ground being the only "true" one. A good way to set this up is during a fast fall up aerial. Outside of this, up tilt has situational use as a frame trap with this at lower percentages.
If Arsene is present when the move is inputted, Joker will instead use Wings of Rebellion (反逆の翼, Wings of Rebellion), which causes Arsene to allow Joker to fly upwards, or at a slight angle. Joker is invincible during Wings of Rebellion's startup, up to Frame 23. However, after this, Joker is completely vulnerable, meaning the Joker player will have to use it sparingly.
Joker does not use a grappling hook in Persona 5 outside of the game's menus, but he does use one when dungeon crawling in the game's updated re-release Persona 5 Royal (a fact which was confirmed a few days after Joker was released, heavily suggesting that the idea for having the grappling hook in his moveset came from Royal).
Wings of Rebellion has no solid base in Persona 5, but is likely based on the fact that Arsene is capable of flight. It is also a possible reference to the intro of the game, which shows Joker summoning Arsene to take flight. The name of the attack calls back to a speech that is heard whenever Joker begins a new Confidant: a voice informs him that the bond he has just forged "shall become the wings of rebellion that breaketh thy chains of captivity."