One idea could be exploring how she balances her pregnancy with her ninja duties. Maybe she has to take on less dangerous missions but still finds ways to contribute, like training new genin while pregnant.
A more complex plot could involve some sort of threat to her pregnancy. An enemy might target her unborn child because of her importance in the village. This would lead to a high - stakes story where she has to fight to protect her future family while also dealing with the physical and emotional challenges of pregnancy.
A plot could revolve around the mystery of who the father is. It could add a lot of drama and speculation. Also, Sakura's pregnancy could be a symbol of new hope in the village. She could be seen as starting a new chapter in her life and bringing new life into the world, which could inspire the other characters to strive for a better future.
Perhaps Sakura, being immortal, tries to find a way to end her immortality at some point. She might be tired of seeing her loved ones die while she remains. She could also use her long life to master all forms of ninjutsu, far beyond what any normal ninja could achieve, and then have to deal with ninjas who are jealous or fear her power.
One plot idea could be that Sakura is tied up by an enemy who wants to use her as bait to lure her teammates. Another could be a training exercise gone wrong where she's tied up as part of a difficult survival test. Or perhaps in a more comical scenario, her friends play a prank on her and tie her up, but then things get out of hand when real danger approaches.
One idea could be exploring how their friends in the village react to the news. For example, Naruto might be overly excited and start planning all kinds of baby - related things for them. Another plot could focus on how Kiba and Sakura adjust to the idea of becoming parents. Maybe Kiba has to learn to be more gentle and Sakura has to deal with her own insecurities about motherhood.
One plot idea could be that Sakura, while on a mission, stumbles upon Pein's base by accident. She tries to use her medical skills to heal some of the injured Akatsuki members there as a way to negotiate peace, which surprises Pein. Another could be a time - travel scenario where Sakura goes back in time and meets a younger Pein before he becomes the leader of the Akatsuki, and she tries to change his path. A third idea is that Pein captures Sakura to use her knowledge of medical ninjutsu for his own purposes, but Sakura gradually makes him see the value of life in a different way.
Maybe Tobirama discovers Sakura's chakra control abilities and decides to study her in order to improve his own understanding of chakra. This leads to a series of experiments and training sessions together, during which they develop a mutual respect for each other's skills and determination.
A more complex plot could be Sakura trying to bridge the gap between the Leaf Village and the Mist Village. As Mizukage, she initiates cultural exchange programs. This includes sharing medical knowledge from the Leaf and learning about the unique water - based ninjutsu of the Mist. Along the way, she faces opposition from traditionalists in both villages but manages to bring about positive change.
One interesting plot could be that Sakura, on a diplomatic mission to Suna, gets lost in the desert and is rescued by Gaara. This encounter leads to a series of exchanges where they both learn about each other's past traumas and how they've overcome them. Another idea is that they team up to fight a new common enemy that threatens both Konoha and Suna, during which they develop a deep respect for each other's skills.
Another plot could be that the tattoo is a mark from a past encounter with an ancient and powerful being. As she tries to uncover the meaning of the tattoo, she gets drawn into a dangerous adventure that involves secrets from the ninja world's history.
One idea could be that Sakura Haruno, as a doctor, discovers a new and rare disease in the ninja world. She has to race against time to find a cure while facing opposition from traditional medical views. Another plot could involve her treating a powerful enemy ninja who holds secrets that could change the balance of power in the shinobi world. And also, she might travel to different villages as a medical ambassador, sharing her advanced medical knowledge and making new friends and allies along the way.