WARNING: The following contains spoilers for Fruits Basket Season 2, Episode 25, "I'm Different Now," now streaming on Crunchyroll.
Fruits Basket concludes its second season with a couple of bombshell reveals about its most mysterious characters. Kureno has kept his distance from practically everyone except for Akito over the course of the season, but after recieving the DVD of the school play from Momiji, he has to say something. He confesses his big secret twice, first on the phone to Shigure (who more-or-less figured everything out to begin with) and then in person with Tohru.
Kureno is the Rooster of the zodiac, but he's never once been seen before in his animal form. When the show finally reveals his avian form, it's in brief flashbacks. Other victims of the Sohma curse end up naturally attracting animals of their kind, but when Kureno meets with Tohru in the park, birds flee from him. If this wasn't enough evidence that something's up with Kureno, he hugs Tohru... and doesn't transform.
Kureno's curse has broken.
Kureno explains that his curse broke many years ago, when he was younger than Tohru is now. He has no clue why it broke, and his feelings around it were mixed -- sadness that he couldn't fly anymore tinging an otherwise deep sense of happiness of finally feeling human. Breaking the Sohma curse also severed his mystical connection with Akito.
He could have freed himself from Akito's control at that moment. However, seeing the young "God" of the zodiac breaking down crying over the severed connection, Kureno promised he'd stay by Akito's side forever. There's no magic keeping Kureno down but only his own sense of loyalty. Even if this loyalty hurts him, isolating himself from the rest of the world and unable to contact Uo, the first person he's fallen in love with post-curse, he can't let himself break this promise to a sad little girl.
Oh yeah, Akito's a girl.
This second twist is maybe less surprising in the anime than it was in the manga, given Akito has very rarely been referred to by gendered pronouns and is voiced by a woman when none of the adult male Sohmas are. Still, this is yet another major shock to Tohru, whose mind has already been blown by the knowledge of Kureno being cured. This twist puts Akito's misogyny in a twisted new light. Season 2 of Fruits Basket ends on this cliffhanger reveal, with the third and final season, set to premiere sometime in 2021, promising to use this twist as the start of explaining the story of the scariest, most powerful and manipulative Sohma.