Another concept is that a Hollow with the ability to travel between universes attacks Konoha. This Hollow has the power to absorb chakra. Naruto and Hinata, along with some Bleach characters like Ichigo, team up to stop it. Hinata might use her Gentle Fist techniques to disrupt the Hollow's chakra - absorbing ability, while Naruto and Ichigo go for a full - on offensive with their signature moves.
One idea could be a crossover where Naruto and Hinata somehow end up in the Bleach universe. Maybe they are mistaken for powerful spirits and are recruited by the Soul Society. They could use their ninja skills in battles against Hollows. For example, Naruto's Rasengan could be a powerful attack against Hollows, and Hinata's Byakugan could help in detecting spiritual presences.
A more complex fanfiction could involve a forbidden jutsu in the Naruto world that accidentally opens a portal to the Bleach world. Naruto and Hinata are the first to be sucked in. In the Bleach world, they meet Rukia, who teaches them about the spiritual energy there. Hinata starts to develop her own spiritual powers, similar to how she developed her ninja skills, and Naruto tries to find a way back home while also getting involved in the conflicts between Soul Reapers and Hollows.
Chapter 87, "Temporary Replacement", is the clearest early answer because it turns Sister Li's situation into a concrete plot event. The chapter gives readers a real answer by opening on Luckily, at that time, Jiang Li had already taken her pot of stinky...
Chapter 394, "I'll Invest One Billion in Your Movie", is the clearest early answer because it turns Shang Shaobai's situation into a concrete plot event. It opens with Jiang Li said, "You don't need to question it, just do as I say, and...
Chapter 195, "Woke Up and the Base Was Stolen?!", is the clearest early answer because it turns Americano's situation into a concrete plot event. The chapter turns that into something concrete by moving from Jiang Yan was fully equipped and followed at the end of the team.
Chapter 63, "Far Exceeded Expectations!", is the clearest early answer because it turns Jiang Li's situation into a concrete plot event. A useful checkpoint is the way the scene starts with During those seven days, he thought he had completely escaped from...
Chapter 286, "I Won't Let Anything Happen to Either of Us", is the clearest early answer because it turns Jiang Li's situation into a concrete plot event. The chapter turns that into something concrete by moving from Throughout these reincarnations, Zhao Lang had gradually discerned a...
Chapter 131, "This Lady is Here to Travel", is the clearest early answer because it pushes Sour Ribs into a new phase or setting. A useful checkpoint is the way the scene starts with Just around mealtime, Director Sun came over pushing his small food...
Chapter 397, "Talent Show Program", is the clearest early answer because it turns Zhou Wenshu's situation into a concrete plot event. The chapter gives readers a real answer by opening on Second Aunt, I know you're worried about Shixu interacting with...
Chapter 168, "Gu Family in the Capital", is the clearest early answer because it turns Capital's situation into a concrete plot event. A useful checkpoint is the way the scene starts with Su Yinwan spoke those words with a pitiable expression, then lowered...
Chapter 565, "Our Homeroom Teacher Isn't As Twisted As You!", is the clearest early answer because it turns Sister Manman's situation into a concrete plot event. The chapter gives readers a real answer by opening on After the ingredients were delivered, Chen Manman handed them all...
Chapter 301, "Stealing Skills", is the clearest early answer because the violence around Long Tassel Spear becomes final instead of hypothetical.