The status of the Highschool of the Dead manga is rather unclear. There were some issues related to the author or publisher, and it just stopped without a definite conclusion.
Well, first of all, the writers often take the unique elements from each universe. From Naruto, it's the ninjutsu, kekkei genkai, and the concept of the ninja villages. From Highschool of the Dead, it's the zombie apocalypse and the school environment. They then find ways to make these elements work together. Maybe a character with a Sharingan from Naruto can use its powers to detect zombies from afar. Also, they might use the character relationships. A Naruto character could form a team with some Highschool of the Dead survivors to face the challenges together. And they might also play with the different values of the two universes. For example, the loyalty in Naruto and the survival instinct in Highschool of the Dead.
It's a story mainly set in a high school during a zombie apocalypse. It follows a group of students as they try to survive, facing not only the undead but also various challenges among themselves and in the chaotic world around them.
There are many great fanfictions about Saeko Yuri from 'Highschool of the Dead'. Some might focus on her character development outside of the zombie apocalypse scenario in the original work. For example, a fanfiction could explore her relationships with other characters in a more peaceful setting, showing a different side of her personality.
It's a visual novel likely based on the 'Highschool of the Dead' series. It probably involves the story of the students in a high - school during a zombie apocalypse, their struggles for survival, and the relationships that develop among them in such a dire situation.