It's also possible that Hana is related to one of Naruto's friends. Maybe she's Kiba's sister or something. And because of her connection to Naruto's friend, Naruto feels responsible for her safety. So when she's in trouble, Naruto steps in to save her without hesitation.
Hana could be an original character created for this fanfiction. Maybe she is a new ninja in the village who Naruto falls for, but she has a hidden agenda that ends up breaking his heart.
To create an engaging Naruto and Hana Hana no Mi fanfiction, start with a strong concept. You could combine a mission in Naruto with the powers of the Hana Hana no Mi. Let's say Naruto and his team have to rescue a hostage, and a new character with the Hana Hana no Mi powers joins them. This character can use their powers to create distractions during the mission, like growing large flower structures to block the enemy's view. Another important aspect is the interaction between the Naruto characters and the new element of the Hana Hana no Mi. Their reactions and how they adapt to this new power can add depth to the story.
Since I haven't read 'boku girl boku no arbeit novel' directly, I can only speculate. However, from the title, it might deal with the concept of identity ('boku girl' could imply something about gender identity or self - perception). Also, 'arbeit' might suggest themes related to work or purpose in life. There could also be themes of personal growth and the challenges one faces in the context of work and self - identity.
A great plot idea for this fanfiction is a time - travel scenario. A character from the future, who has mastered the Hana Hana no Mi, travels back to the Naruto era. This character could use their powers to change the course of history, for better or for worse. Maybe they try to prevent a major war by using their flower - based powers to heal relationships between different clans. Or, there could be a plot where a group of ninja are sent on a quest to find the origin of the Hana Hana no Mi in the Naruto world, believing it holds the key to a great power that can save their village from an impending doom.
One similar novel could be 'Kimi no Na wa' (Your Name). It has a unique story about two people who mysteriously swap bodies and their journey to understand each other. Another might be 'Orange' which also deals with complex relationships and personal growth in a rather poignant way. And 'A Silent Voice' is also a great choice as it focuses on themes of redemption and friendship like many good novels in this genre.
Their relationship could develop slowly. At first, it might be awkward as they are strangers in a way. But Naruto's friendly nature could break the ice. He might share stories about his adventures, which would intrigue Hana. Hana, in turn, could show Naruto the traditions of the Inuzuka clan. They would gradually become friends and then, as they see each other's good qualities more often, fall in love.
Well, without having read 'boku ga yuusha de maou no boku de light novel', it's hard to say precisely. However, from the title, it seems to imply a story where the main character has a dual nature of a hero and a demon king. This could lead to all sorts of interesting plotlines, like internal struggles between good and evil within the character, or perhaps a story where the hero - demon king has to navigate a world that views these two identities as completely opposed.