Futaba is the Confidant that represents the Hermit Arcana. She’s a bit shy, but willing to help you along with the rest of the Phamtom Thieves. She’ll join your crew automatically after 8/31 as part of the story, but she requires a huge time investment since you need to really up your kindness to pursue any further dealings with her as far as Confidant abilities go. Rank 4 (Selfless) is required to keep the bond going, so make sure to read some books and do some work for Sojiro.
It may seem like a chore to raise that Social Stat, but Futaba’s abilities focus on support and allowing you to turn the tables during tricky battles. Her Rank 4 ability, Position Hack, provides a chance to instantly Hold Up enemies at the start of a battle (though you won’t be able to capture any of them). This can only trigger if you didn’t ambush them, meaning it can work if the enemies ambush you instead (which is never a fun position to be in). Emergency Shift, her Rank 9 ability, provides a chance to swap two KO’d teammates with two healthy ones. That can really turn the tables during a bad fight, giving you a leg up on your adversaries.
On top of these skills, Futaba has the usual support abilities such as healing the party, restoring SP (which is very valuable), and even offering a chance to completely nullify a fatal attack on any party member. Not too shabby, not too shabby at all.