One interesting aspect could be fanfictions where Naruto uses the Henge technique in relation to the Kyuubi in creative ways. For example, he might use it to disguise himself as the Kyuubi to deceive enemies. Another could be stories that explore the connection between the Henge and the power of the Kyuubi within Naruto, like how it affects his chakra control when using the Henge in a Kyuubi - related form.
There could be fanfictions that delve into the psychological aspect of Naruto using the 'Henge Bra Kyuubi'. Maybe he has to overcome his own insecurities or fears when using such an odd - looking transformation. It could also be about how his friends and allies react to this new form of his. Some fanfictions might show how the Kyuubi's power is harnessed in a different way through this unique Henge, for example, using it to communicate with other tailed beasts in a more effective manner.
In fanfictions, it often works by Naruto using his Henge technique in a way that combines the idea of a bra (which could be for comical or symbolic reasons) and the power of the Kyuubi. He might transform into a form that has elements of both, perhaps to gain a unique ability. For example, the 'bra' part could be a magical or chakra - enhancing device in the story, while the Kyuubi elements give him raw power.
I'm not entirely sure as it could be a very specific and perhaps user - created concept. It might be a fanfiction where Naruto uses the henge (transformation technique) in relation to a bra in some comical or creative way. But without reading the actual piece, it's hard to say exactly.
One interesting 'Naruto Henge Naruko' fanfiction could be where Naruto uses the henge to transform into Naruko for a stealth mission. He then has to deal with the different reactions from his friends and enemies who mistake him for a real girl. It adds a whole new layer of humor and challenges to the story.
One interesting Naruto Henge Bloodline fanfiction could be where a character discovers a new and unique bloodline related to henge that gives them the ability to transform into mythical creatures. For example, they might be able to turn into a phoenix and use its powers in battle.
One idea could be Naruto using his henge to transform into the Kyuubi in a different way than expected. For example, instead of just looking like the Kyuubi, he could also gain some of its powers in a limited form while in the henge. This could lead to him surprising his enemies and allies alike.
One example could be a fanfiction where Sakura uses the henge to disguise herself as a famous athlete wearing a sports bra for a mission. She has to blend in with a group of sporty people and the sports bra is part of the look she needs to pull off.
He could be buying it for Sakura. Maybe Sakura is in a situation where she needs a new bra but is too busy with her medical ninja duties to go and buy one. Naruto, being the helpful friend he is, decides to use his henge and get it for her.
One interesting Naruto no Kyuubi fanfiction could be the ones where Naruto has better control over the Kyuubi's power from the very start. It changes the whole dynamic of his early battles and how others perceive him in the academy.
One idea could be a female ninja using the henge to transform into the Kyuubi for a stealth mission. She could infiltrate an enemy base while in this form, using the Kyuubi's intimidating presence to her advantage. Another plot could involve a female character using the henge to look like the Kyuubi to scare off some bullies in the village. Maybe she's a young kunoichi trying to prove herself and this is her unique way of handling the situation.
One idea could be that the female Kyuubi form uses her unique powers in a way Naruto has never thought of. For example, she might be able to communicate with animals in a more profound way due to her connection with nature as a nine - tailed fox. Another plot could revolve around how she has to hide her femininity while in the Henge form to avoid unwanted attention in the ninja world. Maybe she struggles with maintaining the balance between her human - like emotions and the wild nature of the Kyuubi.