Haru Okumura is primarily present as a Phantom Idol, or cognitive teammate. She has not yet made any appearance in the main story, outside of her lines during the Sae Palace escape intro cutscene.
Noir is first seen at the very end of the P5 Collab's Pyramid Chapter, after the group is abducted and finds themselves in the space station, as she and Mona are right there in the station to greet them. However, she features much more prominently in the Spaceship Chapter, as this is when she, Mona, and Joker actually join with the rest of the group in order to steal the Core there.
While she's initially a bit nervous to be a newbie in front of this other group of thieves, Wind reassures her, and they later connect over having reduced themselves to their roles for their families and others, before their respective friend groups helped them break out of this mindset. Joker also puts on an entire Beauty Thief routine which she cites as lightening the mood and helping her relax. Still, her father is consistently on her mind as they traverse this place that looks like his Palace.
Noir later unintentionally is the catalyst that makes the group realize they're actually from parallel worlds, as Big Bang Burger (and, it's implied, Okumura Foods as a whole) does not exist in the P5X universe.
Haru can also be found in Leblanc in the real world, which Wonder is for some reason capable of crossing worlds to visit. She won’t appear until Wonder has begun the Spaceship Chapter, but has evidently already heard about him from the others. She talks about her day-to-day activities and hobbies, including asking Wonder for suggestions for what she should grow in her rooftop garden at Shujin.
Noir's Persona Milady is categorized as a Psychokinesis type, and resists Psychokinesis while being weak to Nuclear.
Milady is a Sweeper Persona, meaning she’s good at dealing with groups of enemies, and her trait makes it so that Noir's grenade launcher ammo can gain "Modifications" from her Persona skills, strengthening it (up to three Modifications can be active at once, and they're consumed when she fires her grenade launcher).
Her first psychokinesis attack skill hits all enemies twice, with a chance to inflict a "Crosshair" for three rounds (also grants the "Thermal Energy" Modification: enemies with a Crosshair take extra damage from Noir's grenade launcher, consuming the Crosshair); her gun attack skill hits one enemy, dealing extra damage if they have a Crosshair (also grants the "Armor Removal" Modification: the next ranged weapon attack deals extra damage, and the Thermal Energy Modification can now apply to psychokinesis attack skills as well); and her second psychokinesis attack skill hits all enemies, having an increased critical chance on any enemies with a Crosshair (also grants the "Diffusion" Modification: the next ranged weapon attack deals extra damage, and the Thermal Energy Modification can now apply to psychokinesis attack skills as well).
Her passive skills buff Noir's attack and critical damage based on Noir's effect hit stat, and grant Noir a layer of "Barrel Heat" every time a Modification is consumed (the first layer of Barrel Heat buffs Noir's effect hit and resistance stats, the second layer buffs her defense, and the third layer buffs her critical damage).
As in P5, her melee weapon is axes, while her ranged weapon is a grenade launcher. Her Highlight is shown from 0:47-0:57 in this video, and it deals psy damage to all enemies. If Noir's Modification slots aren't full, it grants the "Overload" Modification: buffs Noir's critical rate when using her ranged weapon. If her Modification slots are full, the Highlight's damage is buffed instead.
Her recommended card sets are 1) 6 of Cups (Pleasure) + Queen of Swords (Wisdom), 2) 4 of Coins (Power) + Princess of Coins (Growth).
The game recommends teaming her up with 1) Summer Tomoko, 2) Rin.
Currently exclusive to Global, Noir has a maid costume as well. The differences with this costume are purely cosmetic.